/ Motoring

Warning lights on? Your car will fail its MOT test

New tougher MOT rules will require your car dashboard’s warning lights to be working. If they don’t, your car will fail its MOT test. Is this a much needed safety improvement or a route to more rip offs?

The MOT test now includes a ‘Malfunction Indicator Lamp’ check. This requires the examiner to visually check that warning lights for electronic stability control, safety restraint systems, anti-lock braking systems and tyre pressure monitoring systems are not permanently illuminated.

The requirement came into effect on 1 January to comply with a revised European testing directive. It will be highlighted as an ‘advisory’ item only until 31 March, but from 1 April onwards, vehicles will fail an MOT if these lights are illuminated.

It’s just a visual check – so doesn’t require any diagnostic equipment to evaluate the actual cause of the light being on, but you can bet your bottom dollar the garage will charge you to investigate why a light is on (it will scan the system for a fault code, pointing to the cause).

The risk of rogue warning lights

When I recently asked my Renault dealer to investigate a warning light, the first thing they said was that there would be a £45 charge for a diagnostic check, then additional rectification costs depending on what that revealed.

My ‘fault’ was a service warning to check the handbrake (not covered by the new MOT rules as far as I can tell) which came on after the battery was disconnected.

As an ex-mechanic, I checked the physical components of the handbrake and there wasn’t an actual handbrake fault. In my view, it was simply a rogue indication because of the loss of power to the system. But to find that out for sure, I have to stump up £45, without even thinking of any consequential costs.

Don’t get me wrong, I completely agree that these lights are important – and if functioning correctly, they can let you know of a genuine safety risk.

So it seems sensible to make these an advisory notice. But, to me, the idea that they constitute an automatic MOT failure (without a proper investigation) leaves motorists open to being charged extra, perhaps simply because modern electronic systems are still too quirky and can display rogue signals from time to time. Would your car pass these new MOT rules?


With your background, Dave, you probably keep a check on the condition of your car and ensure that it is in safe condition throughout the year. You know that you have a rogue warning light rather than a genuine fault. Unfortunately the vast majority of the population know little about their cars and many don’t even check their tyre pressures regularly. Warning lights can provide information about serious faults and without increasing the time/cost of an MOT further I do not see an easy solution. You suggest an advisory notice, but this could be ignored. Since MOT records are held on computer it should be possible for another dealer to notify that the problem has been corrected within a fixed time period.

If there is a design fault you might be able to get the problem rectified free-of-charge by your Renault dealer. The tyre pressure monitor system used by Renault seems unreliable, from what I have been told.

“This requires the examiner to visually check that warning lights for electronic stability control, safety restraint systems, anti-lock braking systems and tyre pressure monitoring systems are not permanently illuminated.”

What a load of tosh, fortunately I only have ABS warning on my car, I would therefore seek to buy cars without these features so that there is no issue.

The graphic shows engine warning, oil and battery but according to the above they are NOT part of the MOT.

All I see here is the motor industry trying to get more money out of the struggling motorist and nowt to do with safety. I see loads of rusty old vehicles on the road with a valid road tax and therefore MOT and insurance.

Before you know it they will be asking for a CO2 pollution certificate based on mileage and exhaust reading – oops maybe I shouldn’t have said that.

@ Dave Evans – to answer your question – its another rip-off unless the car manufacturers guarantee the electrics for the life of the vehicle and thus any intermittent fault has to be repaired at the cost of the manufacturer (NOT the supplier).

I think you are right, David Ramsay, about the manufacturer’s responsibility for electrical systems on cars. Properly designed electronic/electrical systems are incredibly reliable. These are used for process control in industry, and hi-fi separates are a good example of good quality electronics. Mechanical components of cars are never going to be very reliable but it is often the electronic components that cause the problems. If the manufacturers use good quality components well within their ratings, seal everyone including connections to prevent water ingress, and protect the electronics from voltage spikes, and use decent quality sensors there is no reason why we should have the tiresome problems with warning lights and other electrical faults.

Until we can persuade manufacturers to provide extended parts and labour warranties in the cost of products the customer will have to pay for poor design by manufacturers, whether it is cars, TVs or washing machines.

@wavechange – “Until we can persuade manufacturers to provide extended parts and labour warranties in the cost of products the customer will have to pay for poor design by manufacturers, whether it is cars, TVs or washing machines.”

Some issues with this;

1. Isn’t that what Which? should be doing? (Sorry this goes back to previous conversations!!)
2. Under the sale of goods act a design fault is a manufacturing problem which is not being properly allocated to the source of the problem but being left to the retailer to pick up – this IMHO is incorrect, the retailer should be under NO obligation to pick up the tab but he should be able to pass the detail of the manufacturer to you along with relevant supply details (batch number etc) so that you can contact/sue the manufacturer directly.

We DO NOT have to pay for poor design

David Ramsay
Which? does assess durability of products but obviously it would not be practical to keep a car, TV or washing machine on test for years.

At present, the retailer is responsible, and this is a particular problem with car dealerships, which sometimes close or change hands frequently. I once tried to get my variegated Volkswagen repainted (some parts were still bright red but others had faded badly) but the dealership had closed and VW claimed that the problem was due to how I had kept the car!

If a problem fails outside the warranty period the purchaser currently has to get an expert to provide a statement to the effect that the fault was present at the time of manufacture to pursue a claim under the Sale of Goods Act. If a sensor fails on a car, that would normally be easy to spot, but car electronics are often sealed or encapsulated to keep out moisture. That will make it difficult or impossible to establish the cause of failure. I don’t think the Sale of Goods Act is a great deal of help to most of us, most of the time.

Which? did not recommend vacuum cleaners because of their poor reliability. When Dyson extended their warranty, Which? started recommending them, though other brands remain more reliable.

With a car, many problems can be due to carelessness or poor maintenance, but it is difficult to abuse electronic monitoring and control systems. That is why I believe that these should be covered by an extended parts and labour warranty. I agree – we should not be expected to pay for poor design.

Until this happens we should push for compensation if a car or other product suffers from a well know problem. Thanks to Internet forums, etc. there is often plenty of evidence that a problem exists.

Now this is an interesting one. When I saw the title of this conversation I thought ‘good idea’ but your post has got me thinking.

My car for example once or twice a year decides to pop the power steering warning light on upon start up of the engine. I had this looked into at the time and nothing was found to be wrong, the mechanic pretty much came to the conclusion that it was a case of the on-board computer being a bit too eager in the cold weather as this warning would soon go away once the car had warmed up and been restarted.

I do think that this could potentially make putting a car through an MOT much more costly for the consumer.

I won’t pretend I’m a massive car nut and that I know what an MOT test actually checks but why on earth would you fail purely on the basis of a light? Surely the areas which the lights, under the new rules, would fail you on should be areas tested by the MOT tester anyway?

Paul Johnson says:
9 January 2012

Why do we follow the EU directive for this, but not the EU directive for the frequency of MOT testing? The EU standard is 2 yearly. (Actually I know why : vested interests )

Having a yearly MOT test helps keep unsafe cars of the road, Paul. There was a lot of discussion about this in a Which? Conversation last year. Even with the current yearly test, the failure rate is worryingly high. Considering the other costs of motoring, I don’t mind paying for an annual MOT test.

Actually I believe the government are considering changing to a 2 year cycle for MOT.

That’s right David. More deaths on the road. I hope it won’t be your family or mine.

In a country that seems to be obsessed with health and safety over trivial matters (remember the council that warned people about the dangers of conkers falling from a horse chestnut tree), it looks as if we may not need an MOT until a car is four years old and then only every two years until it is ten years old. Bearing in mind that most people have their car checked only when the MOT is due, this is not very clever. It will make insurance higher for everyone unless the insurance companies give discounts to those who have an annual MOT test.

Derek Stevenson says:
9 January 2012

As you can get cheap OBDII readers from the likes of e-bay (around the £20 mark) there is no real reason to pay Renault (or any other manufacturerer) whatever absurd anount they charge to check the cause of the problem, these can then reset the lights and any “old” fault codes stored in memory.

If it then proves to be a “livel” fault, the warning light will illuminate again and you will then need to get it investiagted as it will be a real problem and thus should in my opinion be an MOT failure.

Perhaps this would be a good oppertunity for WHICH to do a test of OBDII readers??

Well, firstly I would think a panel light check would only apply to “safety aspects” ? So, oil warning, battery, handbrake and even engine management lights although very desirable to be fully functioning wouldn’t count. These are not safety elements which is what the MOT is supposed to be all about.
This means Dave that the “Which” graphics people were not perhaps fully briefed?

The lights in question must relate to things like “ABS” (antilock brakes) and “ESB” (electronic stability control) and the like.
I thought a permanently illuminated ABS light was already an MOT failure? A permanently illuminated ABS light indicates the system is faulty? (the bakes will work, but they won’t be antilocking)
Anyway, while it is still often possible to buy the same model of car both with and without ABS I don’t really see the point. Although I’d conceed that if you have it it’s preferable it should work.
I can understand (if not agree) why the EU directive compilers (who need to justify their existence) have done this. They think these systems contribute to overall road saftey if they work.
Thing is if these systems don’t work the car is no more dangerous than the cars not fitted with these systems, which will pass the MOT, “safety test”.

Like you I think the current advisory system is sufficient, and the new rules just gives some testing stations an excuse to raid bank balances.

I’d like to see the manderins of the EU spend a bit more time trying to improve road safety by looking at the standard of performance of by far the most important safety element of any car, that being the driver.
While they’re at it if they really want to make roads safer they might also take a look at the over sign posted, over traffic lighted and generally poorly planned road system we put up with, which I’m sure contibutes to accidents through driver frustration.

The purpose of an advisory notice is to alert the state of a component whose condition would not be grounds for failure on the day of the MOT test. These are typically components that will continue to deteriorate with wear, corrosion or age.

A common example is tyre tread depth. It might be OK to get throught the MOT test today, but after a few hundred miles and you could be prosecuted for driving with illegal tyres.

And, by definition, a warning light is something that the driver should already be aware of. It doesn’t require an MOT advisory to draw it to their attention.

So an advisory is not an appropriate way to deal with a warning light. Either warning lights are within the scope of the MOT test or they are not. And if they are in scope, they either work, or they do not. If they do not work, then it’s a fail condition, plain and simple.

I find it amazing that people drive around with warning lights illuminated. Unless they have the technical knowledge to be sure that the light is malfunctioning, how do they know the car is safe to drive? Even if this is the case, how will they know if a fault does occur?

Precisely Wavechange. So I felt it was the right thing to do, when I wasted most of last Saturday having my brakes checked over.

The BMW garage had only replaced the pads and discs in the summer, and the previous set had lasted me for 70,000 miles. I knew they hadn’t reset the service indicator correctly, but when the brake warning light came hard on, what was I to do? Just ignore it until the next service date and potentially mask a second fault in the mean time?

Make that mistake in an aircraft and you’d be shot for negligence (assuming you don’t kill yourself and everyone else first). I don’t understand why motorists think the same standards of safety don’t apply to them, just because their wheels don’t leave the ground and it might cost them the price of a tank of petrol to sort out. In my case the garage acknowledged their mistake and put it right at no cost.

I hope this isn’t official Which? policy btw, or I’ll save my subs and put it towards having my car serviced. We don’t need mixed messages like this; there are enough idiots out there without giving them further excuses not to maintain their vehicle properly.

This topic is up for discussion and my understanding is that nothing posted by Which? staff represents Which? policy unless this is stated.

I would like to see random inspection of vehicles for obvious defects, which could include safety-related warning lights. Say £20 compensation if the vehicle passes and fines for those whose vehicles fail. It might save lives and encourage some people to behave responsibly. There are so many vehicles that are unfit to be on the road that the scheme would pay for itself.


This comment was removed at the request of the user

michael gerrard says:
23 June 2021

Someone I Knew worked at a local dealership as a mechanic servicing German cars. He told me that they sent out every 4th car with a fault ensuring repeat business. Re the mot fail another friend has just paid out £420 following his campervan failing due to a faulty warning light on his dash, the dealer quoted £120 per hour. Dealers, The Mot etc are just rip-off merchants

Alwyn Green says:
13 January 2012

This is very unfair. It has nothing to do with roadworthyness and seems to be another case of MPs making laws to enrich vested interests, this ytime in the already questionable motor repair trade.

It looks as if my permanently-on “Service Required” light may not be subject to the MOT – but is it? If it is, then I would have to go to Volvo or one of their dealers to get it switched off (my car being 12 years old, and the light not being switchable electronically) as part of a service, and doing that would cost me an extra £300 or so. £300 being the Volvo cost premium over the cost of an ordinary garage service. I would not be pleased!

This a complete nonsense, a price-gouging ramp promoted by the car dealer trade as a revenue-earner. The results are often ridiculous and expensive.
Example: my son went for his driving test in my wife’s car, which for years has had the airbag warning light permanently on. These are nowadays connected also to the seatbelt tensioners – and therefore have wires to sensors in the seats. These wires run under the seats, and are very frequently broken or disrupted when rear passengers put their feet there.
The airbags are NOT part of the MOT Test. But the examiner, half way through the test, noticed the light was on. He stopped the test on the spot, said that the car was “not roadworthy”, and “not fit to take the driving test in”, and abandoned my son at the side of the road.
Even if you rejoin the sensor wires, the light remains on, recording the PAST fault, until it is reset by a authorised dealer – who can charge up to £250 for this service.
It’s a licence to print money for the motor trade. Nothing else.
All sensible people will simply disconnect the light connections.

I hope you made a complaint about the examiner since he left your son without supervision in charge of a vehicle without a full licence.

This is an offence as far as the Police are concerned and IMHO the examiner should be reprimanded. At worst he should have abandoned the test and asked your son to drive the vehicle back to the test centre.

From the point of view of the cost under the sale of goods act the warning system needs to be fit for purpose, if the problem can be shown to be because of poor design then the retailer is (currently) responsible for the issue and he should repair free of charge.

I wonder what the Automotive trade associations have to say about this? How about it SMMT?

All sensible people will simply disconnect the light connections.

I can understand your frustrations but suggesting that we should disconnect warning lights is neither sensible nor responsible. If you have the technical ability to disconnect sensor wires warning lights, why not just get on an repair the defective wiring?

John says:
13 January 2012

I had a warning light illuminated for some time in my Vectra. I was told by my Vauxhall dealer that water, from a deep puddle I had driven through, had got into the Aircon ‘loom’. However that particular model did not have air conditioning, though the ‘loom’ was fitted as standard, so the light was totally meaningless, and did not go out until the ‘loom’ had thoroughly dried out some days later.

It is common practice to use the same wiring loom across for the range of models of a car and it would be uneconomical to do otherwise. I am grateful for this because it has made it easy for me to fit a second rear fog warning lamp, making use of the existing lens.

Unused connections should be covered and sealed to prevent ingress of water, but I have seen many examples where this has not been done.

It is good that the Vauxhall dealer has explained the problem and hopefully the information has been passed back to the company.

If warning light problems start costing people money as a result of MOT failures then there is going to be a lot of pressure on dealers and manufacturers to improve their designs.

Alan R says:
13 January 2012

The problem is that we have too many people driving a ton or more of metal, often at 70 mph who really should not be driving. Nearly everyone wants a car, but many cannot afford to run one and properly look after it to ensure it is safe to drive (even if they are not safe to be driving).

Another problem is, as noted by many others, that rogue warnings often show up. The cheap diagnostic tools may be some help, but they only help with a few of the problems.

My wife has recently had a problem with a Corsa with the easytronic auto gearbox (some of you may know of the difficulties!). Our local garage and a Vauxhall franchise garage could not determine the definite problem and wanted to spend hundreds of pounds without a guarantee of success. The electronics are so interlinked that it appeared to be impossible to sort out what the warning lights were showing.

Until the warning systems are much more reliable it is unfair to make any warning lights an MoT failure, although I would be quite happy for it to be so at a relevant time in the future.

Just out of interest did you have the Corsa “fixed”? If not isn’t there a little bit of hypocrisy here?

Not ‘flaming’, just interested as to the outcome?

Trevor Fleisig says:
13 January 2012

Hello i ‘ve just read your email over warning lights. I do have a warning light that permanently stays on. Bearing in mind how damm expensive it is to run a car this does sound an absolute con. Best wishes for all that you do from Trevor in Sevenoaks.

My wife’s Vauxhall Corsa (1.2 manual) has been displaying the engine system warning light for about 2 years. When it FIRST appeared, we took the car to our reliable independent garage, which advised that there was no obvious problem, and that this was almost certainly a faulty display and not worthy of detailed further investigation in the absence of any obvious problem. Given that it has now been displayed continuously for 2 years and about 25,000 miles (on a 2000Y car with 135,000 miles on the clock) with no adverse consequences I am inclined to agree. To rectify the faulty display will involve removing the dashboard as a minimum. More unecessary expense. I guess eventually the powers that be would like there to be a Logan’s Run scenario where all cars are crushed when they reach a certain age.

Don’t want to turn this into a car clinic but I had a similar problem with my daughters Corsa. This was a 2003 diesel and the little light which looks like a car with a spanner kept comming on, but not all the time. Seems there is a service interval system built in to the “brain” which I thought might be something to do with it.
Turn on the ignition (no need to start) with the mileage reset button in the speedo pressed in. You’ll get “insp” then after a few seconds four dashes. This resets the service interval thingy, and in my case sorted out that light that kept comming on.
Might work for you might not, but perhaps worth a try?

To get back on topic, what if a car fails an MOT on something simple as this?
Few of us have much confidence in the abilities of main dealers to resolve little problems like this and we could end up being parted from hundreds of pounds of our hard earned cash with no guarentee of a result.
I say if the car passes all the mechanical safety checks then it should pass the MOT. Warning lights should be an advisory.

Rebecca says:
13 January 2012

I have a warning light that has been on for 7 months! When it initally came on I went to the mechanic and had it checked – diagnosed by computer. It turned out that the emmisions sensor in the car was not working when I started the car for about a minute or so as it was ‘lazy’ – this sent the wrong signal to the engine and thus put the light on. My car did not register when it did start working and thus left the light on – what my mechanic called a ‘brain fart’!! He told me not to worry about it, that a new sensor would cost about £90 and that as the old sensor was working and the problem lies with the computer I could not really fix it….. is this the right advice?! Do I need to replace the sensor anyway and see ….. it seems to me that this extra requirement of MOT is indeed going to cost me money I don’t need to spend, and when my insurace is actually more than the value of my car for a year – no kidding – I REALLY feel that a lot of people are simply making money with no care or concern for anything else! When these things are challenged they just seem to be blaming computer ‘insurance risk’ programmes or on board computer glitches and saying we need to adhere to the system but when the system is geared to making MONEY and not serving the community then I believe the system will lose the vital ingredient of COMMON SENSE!!!

TonyP says:
13 January 2012

I believe the new rules are sensible and will make owners take action of these warnings which could cause problems in future or compromise safety. Would you want to fly on an aircaft with a warning light showing in the Pilots cabin? Its the same technology.
The “Rip Off”, which will unquestionable occur, is the fault and attitude of the automotive industry not the legislation.
My advice is to keep away from main dealers and find yourself a local independant motor repairer with a good reputation. I leaned this a long time ago when I owned a Porsche 911.
Erroneous warnings are common (look how often you get them on your computer screen). In my experience independants will connect diagnostic equipment and give advice without making any charge.

Ah but a lot of independents cannot purchase the correct diagnostic equipment.

One thing about all this tho is the computer software, now I agree that the original engine/car management systems would be very underpowered, these days tho you can get a very powerful computer for a few pounds.

Now why should we need a dealer to attach diagnostic equipment, surely the computer system should be able to explicitly tell you in plain language what is wrong with the vehicle, its not rocket science if a warning light comes on its because something is detected which requires attention.

Indeed the computer system could refer you to the correct part of the manual or even display the manual on your tablet at the correct point.

One other thing is warning lights which remain on even tho the fault no longer exists, it too is NOT beyond the capability of the computer system to maintain a log locally of anything that happens but once the ignition is switched off and then on again a self diagnostic should be capable of correctly displaying ‘current’ fault(s), after all that is what happens when a computer starts up.

The history is then available for anyone to read until the vehicle is scrapped.

I completely agree with David about the need for fault diagnostic systems to explain the problem in plain English. If motor manufacturers cannot manage this in the 21st century they are doing us a disservice.

I also agree about the diagnostic systems need to be in plain english. Wouldn’t it be wonderfull if car manufacturers provided a full workshop manuel on disk with each car sold. This is supposed to be the age of information except of course for the motor industry. Another porblem can be even when the fault location is known the expense can be serious. I have one in my central juncion box and the replacement costs is over £500. What a rediculas situation. I would rather go back to the old system where a driver could be relied on to check his light etc were working – get rid of this over suffisticated electronics and get rid of the high prices to repair.

The core safety of the vehicle should be the essence of the test.
If it gets too complicated, it will get costly.
If it gets costly then people will find ways around it and the object will be defeated.
Keep It Simple Stupid (KISS) is the way to go forward.

Stan Matthews says:
13 January 2012

i bought a car where the abs indicator lamp had been modified by the installation of a relay which meant that the system appeared to be operating correctly, it was only when i really needed the abs did i discover that it didnt work, it was only after the crash that the relay was found, so if its that easy to overcome i see no point in including it in the mot surly the brake testing machines need to be improved to test the correct operation of abs etc not just rely on an indicator which can be modified to look right.

The person who made the modification should be in prison.

If it is possible to plug in diagnostic equipment into any modern car, surely it would be possible to display the information in the car (if provided with a suitable display) or on a simple, inexpensive display that will work with ANY make of car. We have standards for all sorts of things, so car manufacturers need to get their act together and devise a common standard. It will not happen overnight, but the sooner they get started, the sooner the problem will be fixed and car owners will be less perplexed about what is wrong with their cars.

I think I said that a couple of comments above, but indeed they could but then the dealers would be p….d because they would lose income to run the diagnostic.

I suspect that this could be a nice little earner for dealers, whose profit margins on new car sales have been cut by competition, especially from online traders.