/ 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?


I did rather sourly reflect on the irony that an apparent glitch in the instrument cluster of my VWAG car temporarily rendered it unable to display the status of some warning systems, and this included the ABS warning light. Rather inconveniently, I could not start the car until I interrupted battery power for an hour. Meanwhile, the system was smart enough that the ABS knew it was unable to report it’s Good Status to the instrument cluster, so logged a fault in the ABS that then shows as a latched ABS fault when the instrument cluster got over it’s glitch. So it wasn’t a real fault at all, but the ABS warning light was latched and the car would have failed an MOT. Time and expense later, I located a friendly vagcom guy who sorted out clearing the latched fault, confirming it was the instrument cluster dropping the ball, and not in any way attributable to the condition of the ABS,
Better (more resilient) system design, please.

g boulton says:
6 January 2017

just had mot on my proton,failed purely for hazard warning switch not flashing when switched on.Spoken to numerous people in the trade and its 50/50 wether this is a requirement as long as lights are flashing and it shows them flashing on the dash,


My car also failed on this a few years ago. The switch replacement was pretty cheap.

Bobbydoc says:
11 February 2017

I have an amber power steering malfunction light on my dash, but the power steering works fine with no problems. It cost me £2500. and eight weeks without a car to have it fixed, the diagnostics came up with a body error code. A specialist stripped down the steering and wiring, downloaded a new updated E C U and B M U programme from Ford USA, TWICE! fitted various electronic sensors and switches. But the Amber light is still on. The Garage got fed up of looking at it and said to me there in no fault but the light won’t go off!
So a £80000. Car when I bought it, only passed its MOT because it has flumexed the specialist, who passed the MOT for me. The light came on in December 2015 and it is still on now,but the power steering still works without any problems.

Julie mcgrann says:
21 December 2017

Our Vauxhall Meriva dashboard showed 3 different codes. One was a rear light. The garage said they’d changed the bulb and when we drove off the code was still up as faulty. As well as the other two codes. One of which was another light, even though that also was working perfectly.

We had taken the car in because the power steering sounded odd, crunchy, this wasn’t a fault listed on the dashboard fault lights though!
They fixed the power steering pipe at £150 total and said it would need to have a diagnostic evaluation for the warning lights which he couldn’t do.

We had a diagnostic evaluation that cost £35 and left the car to have the “necessary” repairs!
That cost us £195
This garage told us the fault indicator light that showed the airbag light fault would have to be done at a Vauxhall garage!
As we drove off the car still showed the 3 faults on the dashboard! One of which was still the rear light, even though it was working.

This led me to believe there is a malfunction with the fault finding system! Showing rogue signals!

What can be done?

Susan says:
30 March 2018

My Toyota auris just failed its mot just because 1 of my indicator lights on dash didn’t light up. Surely that can’t be a fail. All exterior lights working fine.


Regulations are regulations rules are rules laws are laws and MUST be followed or you face the consequences Susan If no one broke laws rules etc. there would have been no need for them to be made


Susan – If one of the malfunction indicator lights does not work when tested (for a short period after you turn on the ignition) it would not warn you of a potentially dangerous problem such as a fault with the braking system.

Graham Ruddock says:
4 June 2018

A £400 light Bulb!!!
My son’s Chevolet Spark would have failed its MOT because the dashboard indicator light to show that his rear fog light was on was not working. I don’t have an issue with the need to have such a working warning light, but the indicator was a failed LED on the binnacle circuit board in an area sealed behind an opaque screen. The only solution was to buy and replace the entire instrument binnacle. The part cost was around £300 plus around another £100 to fit and would have taken around 10 days to import to UK. I suspect such a replacement could cost a great deal more on other makes and models of cars. Without it, no MOT.
Actually, we were lucky to find a SH binnacle from a car breaker for £50 and changed it ourselves. That really was lucky, as there were not going to be many working binnacles lying around for a Chevy Spark.
Clearly, the binnacle was not designed to allow the ready replacement of such warning lights, nor a simple repair. This could represent yet another significant additional cost for all motorists. Whatever teh potential cost, I advise you check your warning lights WELL BEFORE your next MOT.
Oh yes – and disabling the rear fog is not permitted. Providing a separate panel mounted warning light may have been the only other affordable option (NEWS BULLETIN: shares in Halfords rise – too late for Maplin!).


This problem only exists because we have allowed manufacturers to design products that are easy to assemble but very costly to repair. With cars it means and expensive repair whereas with TVs and washing machines the failure of an inexpensive component can result in a product being not economically repairable. We now have cars where the engine has to be lifted to replace the timing belt and some where the front bumper has to be removed to replace a headlight bulb.


Which is why I’d like Which? and others to look at repairability – feasibilty and cost – as part of a product assessment. Common vulnerable components should be simple to replace by the owner. On a car this should include lights and routine service items. The complexity of cars these days – particularly electronic items – are integrated for technical, reliability and cost reasons. The risk of failure is often very low. It maybe we need EC regulations to address the problem.


It’s such a general problem that the only workable solution is to have legislation, in my view. Thinking about Graham’s example, is there any car currently produced where it would be a simple job to replace a LED or other minor part in an instrument cluster. With good design that could be easy. I’m not suggesting that manufacturers deliberately set out to make parts difficult and expensive to replace, and it might just be because products are designed for ease of assembly rather than maintenance.


Such items as LED’s are probably rrgarded as so reliable- certainly as low power indicator lights – that integrating them in an electronic panel is sensible. Probably a good deal more relisble thsn making them replaceable. But routine serviceable items should be easy to get at, like an exterior light bulb that fails – usually when it’s dark 🙂
.EC construction regulations could achieve that. We could apply the same philosophy to domestic appliances.


I’m not referring to the LED but the cost of the assembly and fitting, Malcolm. Graham gave a price of £300 plus an estimated cost of £100 for fitting.

I cannot think of any reasonably modern car where it is a simple matter to remove the instrument panel and I know of a few where it is very difficult. Thanks to poor design, failure of a component worth pence can result in the consumer being charged hundreds of pounds for a repair. I agree that construction regulations are the way forward but it would be far better if manufacturers behaved sensibly in the first place.

Occasionally manufacturers do make our lives easier. The switch assembly for my car lights can be removed and replaced within seconds. Unfortunately replacing the adjacent headlamp levelling control would be a major job.


While its easier to blame the actual LED in all the dealings I have had with indicators namely LED,s when building electronic equipment I dont ever remember there being an actual LED failure . I have equipment from the advent of Led,s and all are basic circuits – a stabilized current supply(simple) and a connection to the relevant signal input . A car LED indicator will have a CONTROL sensor chip /circuit in modern cars not a simple wire going back to the component , this is due to modern car processor’s (engine management systems) having ONE big multi connection chip through which all incoming signals are passed and processed I would be surprised if it was simply the LED . But say it is – its easy enough to swap it just get it the right way round and solder in .


I had wondered whether to mention that car electrical systems are not necessarily simple the days and anyone who wants to find out more can look up the ‘CAN bus’ system that is used in cars.

There is a general problem that repairing modern products can be much more difficult and expensive than in the past, and with better design that need not be the case. As you say, it’s probably not as simple as a faulty LED, so perhaps this was not the best example.


The point I was suggesting was that when something is inherently reliable, replaceability is less of an issue. It is expensive to remove and strip a gear box should a bearing fail, for example, but relatively unlikely. Sometimes integrating components can lead to a more reliable and cheaper assembly than if they were individually repaceable. But I do think that wear and tear components and those of limited life should be relatively accessible and easy to replace.


Why not design cars so that the instrument panel and other components are readily accessible by making it easy to remove the dashboard? That should not significantly increase the cost of assembly but would make repairs easier and less expensive. Perhaps the manufacturers should be given a deadline to improve cost effective repairability and if this is not effective then go ahead with legislation.

I’ve made the point about integrated assemblies being cheaper to build and possibly more reliable but this can easily make repairs to cars extremely expensive, as has been mentioned by other contributors to this Convo. Replacing washing machine bearings was once a simple job but thanks to the tank and drum being an integrated assembly in most modern machines it may not be economically viable to effect a repair.

After my MOT I will be booking my car in for a service and replacement of the timing belt. I expect that the latter will be an expensive job, as with my last car. With the previous cars I did the job myself without any problem.

I’ve never had a problem with a gearbox but yesterday a friend told me that he has had a second one fail in his Renault van.


If you are talking reliability Wavechange , I was driven home in a “saloon car ” ambulance and speaking to the driver I was surprised to find it was a 2.5 L diesel (big engine .small car ) .He said it has done over 200,000 miles and in the 30 mile journey I could not hear any wear in the engine , nor the usual click.clack of a diesel. It was a Honda , the drawback ? for a diesel it only did 40 miles to the gallon. If I wasn’t a Ford man Honda would be my second choice.


There is no doubt that car reliability has improved greatly over the years and you no longer need a diesel engine for reliability. In nearly six years and 50k miles I have not had to spend a penny on anything other than servicing. A friend’s Polo with a small petrol engine has done 186k miles and it’s still running fine. I noticed that the engine management light was on but apparently the emissions are unaffected so the car passes the MOT after the garage resets the light.

If you are unlucky, the cost of car repairs can be horrendous.

Graham Ruddock says:
21 June 2018

Can I first of all congratulate the contributors that responded to my comments for the quality of their arguments and thus the value the ensuing debate – some very useful suggestions I feel (if it had been on the BBC’s Have Your Say site, someone would have blamed the whole situation on Brexit!).

Having successfully help my son fit the new S/H Binnacle, I can report that subsequently, the MOT was successfully delivered. Getting the existing dashboard apart was the fun bit. A couple of screws were fairly easy to find and access, but two small screws were behind the steering wheel. Eventually I realised that if you rotated the steering wheel to a particular angle, it was possible to get a screwdriver onto them. That left the screws that were accessed from behind clip-on plastic covers. That is where we all get extremely nervous. Where and how to apply the necessary force, which side of the joint line is to be pushed inwards and how much force to apply. In fact, the garage had broken one cover piece trying to prize it off, but fortunately that was on the part being replaced.

So my contribution to the debate is for there to be a requirement for a few standard ways to indicate how and where to “unclip” clipped together components – even if that upsets the “purity” on some designers concepts (just consider that a challenge to be integrated into the visual design). There is a standard marking for AC and DC power adaptors which we all have learnt, so a simple symbol system like that ought to be possible. As this mostly applies to plastic moulding, they should be simple to incorporate.


Car repair handbooks that show how to do such tasks would be useful. I had a BMC one for my first Mini, and Haines manuals are helpful, but they only cover more popular models. Whether they go into such detail I do not know.

My sons always look on YouTube and forums when they have a car problem that, they tell me, help in both diagnosis and details of the repair operation.

William says:
24 July 2018

I’m afraid the law is an ass! Dashboard warning lights where originally put in for the drivers peace of mind, not for an excuse to right off hundreds of thousands of cars!! They aren’t reliable and are always malfunctioning. Most of the warning lights don’t cause the vehicle to be dangerous and should never be included in the test! As I said, it’s another government scam that mainly affects the poor!


Engineering wise William could have a point , yes I know Safety but when it could be —the wiring- the sensor even the cars CPU if connected it begins to look like manufacturing collusion to sell more cars. Guess what it was in my car ??? – the SENSOR (broken off ).


I would have hoped that most people would want to know if their car had a fault that could affect safety. The problem is simply that warning lights can sometimes illuminate when no fault exists or the fault has been rectified. If there is a design fault with a particular model of car then perhaps owners should be making claims for compensation.

I wonder how common the problem of rogue warning lights is. Like many people I know, I have not had a problem.

Gary jamieson says:
16 January 2019

Bought a car, on finance. Since, having it. NO, traction control or abs. No, lights, on dashboard. Tracking, was out, resulting. Low speed, kerbing. A puncture, not a scratch, on alloy’s. Dealership, saying it’s cause of kerbing. That lost, everything. Although, never, had warning lights!


Gary the first two present a danger to you and any passengers , the second -illegal (no lights on dashboard ) and your right tracking well out causes your car to steer either towards the kerb or into oncoming traffic as well as ripping the tread off your front tyres .
Its their fault . read-