The check engine light is on in my car, what should I do?

The orange glow of the check engine light on your dashboard can be quite alarming, no matter if you’re a mechanically minded driver or not.

Luckily, that amber glow rarely preempts something quite as catastrophic as a soon-to-seize engine and a world of financial pain, because the enigmatic check-engine light has many causes.

However, if do you notice your check engine light is illuminated or blinking, it's important to get your car checked as soon as practicable.

The check engine light will either flash or remain constant, depending on the issue at hand.

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🟧 Steady check-engine light

Book a service

If the light remains solid, then the problem likely isn’t serious and, providing there are no other warning lights, the engine sounds and feels okay and the water temperature is normal, you should be alright to keep driving. Just be sure to get it checked out as soon as possible.

Quite often the check engine light will come on because the car’s ECU determines fuel isn’t burning properly. This could be caused by all manner of simple issues, from a faulty oxygen (or O₂) sensor, mass air-flow sensor, spark plug or coil issues, and even not tightening your fuel cap properly.

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Blinking check-engine light

Take action

A flashing check-engine light usually signals something more sinister such as unburnt fuel being dumped into the exhaust system with the potential to damage the catalytic converter. You may also notice reduced power or rev range in tandem with a blinking CEL, often referred to as ‘limp mode’.

Like the check-engine light itself, limp mode is a warning, not a failure, so if careful you should be able to get your car home with a flashing check-engine light. It pays to be extra-observant, of course, listen for any unpleasant noises and get your car checked by a mechanic as soon as possible.

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Diagnosing the problem

The first thing a mechanic will use to find out why the check-engine light is flashing, is a diagnostic scanner.

Typically, for cars built after 1996 this means an OBD2 port under the dashboard, however Europe moved to the standard later than other regions (in 2001), so take every case as it comes as some cars may need an expensive adapter to carry out diagnostics.

In any case, the vehicle’s on-board computer will have logged one or multiple fault codes, all with an individual values that can be cross-referenced with repair manuals. This code helps quickly rectify the problem without having to spend a lot of time troubleshooting. The scanners also turn the check engine light off once the issue has been fixed.

ODB2 scanners are easy to use and cheap to buy – as low as $20 for ones that let you read the codes on your phone via Bluetooth. Alternatively, you can have this done at an auto accessories store for around $10-$20.

The good thing about DIY diagnosis is you can have a good idea of what’s wrong with the car and know what action to take, so no mechanic tries charging you a $200 diagnostic fee just to tighten the fuel cap.

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If the check engine light comes on

A check-engine light is rarely as serious as you first expect and you should be safe to continue driving with it illuminated.

However, if you’re in any doubt, it’s worth visiting a dealer or independent mechanic as soon as possible. It pays to have a good relationship with your mechanic, as they may even be able to help diagnose the fault over the phone.

And remember, a $300 ride on a tow truck now is much more affordable than replacing major engine components in the future.