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What is the engine management light?

If you have seen that recent AA ad with the little girl happily sitting in the back, lip-synching to Ike and Tina Turner’s Proud Mary, while the car’s engine management light suddenly comes on, you could be forgiven for allowing yourself a cynical shake of the head. The father’s expression of mild, quizzical consternation as he pulls in is probably not what you or I would experience in the real world, with a car playing up and a screaming two year old in the back.

It raises a valid point, though, and not just that cute toddlers and classic rock are ingredients that guarantee a good advertising campaign. The engine management light – it is possibly the scariest invention in motoring. It could mean nothing; it could mean a four-figure repair bill. It definitely means you are not in the mood for lip-synching.

Let’s take a calm look at what it is and what you should do if that dreaded light comes on in your car.



The light is connected to the electric control unit (ECU). This is, in essence, the engine’s “brain,” from which it manages all those processes that keep your engine running smoothly. If the light comes on, something is amiss but the trouble is, you do not know what until someone plugs a laptop into your ECU.

Take the car to a garage, or if it is under warranty to the nearest main dealer, and they will be able to take a look straight away, by talking to the ECU and finding the fault code that has triggered the engine management light. Often, the problem is something simple and trivial, such as a sensor playing up, but it could also be something more serious, such as a fuel injector problem or an issue with the pollution control valve.


Resetting the engine management light

With the problem diagnosed and resolved, the garage will reset the ECU and the engine management light should go out. Make sure this happens, and do not leave the garage till it has done so. Sometimes the light stays on and needs either a second reset or a software update.

Either way, get the garage to sort it out then and there, and do not be soft soaped into driving away with the vague assurance that it will go out of its own accord after a few miles. If the light is on, there is a reason for it, and if there is no reason for it, the garage should be able to make it go out.

You would be surprised at how many motorists end up driving around with an engine management light constantly showing simply because the garage failed to reset it properly. Not only is this disconcerting for the driver, but it could also cause big problems, as you will not be notified if a real fault occurs. It can also present you with a major headache if you try to sell the car on.

Closeup Hand Driving A Car