Engine Light On — What Should You Do? Causes & Solutions 2026

Your engine light (also known as "check engine" or MIL — Malfunction Indicator Lamp) has just come on. Don't panic — but don't ignore it either. Here's what to do, step by step.

Is it dangerous to keep driving?

It all depends on how the light behaves:

The 10 most common causes of the engine light in Belgium

How to diagnose with an OBD2 scanner?

Rather than paying €80-150 at a garage just to read a code, do it yourself in 2 minutes:

1. Plug the OBD2 scanner into the port under the dashboard
2. Turn on the ignition (without starting)
3. Navigate to "Read DTC codes"
4. Note down the code (e.g. P0420) and check our complete list of OBD2 codes

Can you clear the engine light without fixing anything?

Yes, technically, but the light will come back on if the problem isn't fixed. Clearing it is useful for checking whether the problem was a one-off (e.g. a loose fuel cap) or something ongoing.

Engine light and the roadworthiness test in Belgium

In Belgium, an engine light that's on during the roadworthiness test generally results in a failure, unless the inspector determines it's a clearly identified minor fault with no risk involved. Clearing the code just before the test isn't a lasting solution: the OBD monitors then reset to "incomplete", and an inspector using a diagnostic tool can spot this immediately, which can also lead to a failure. The only reliable approach is to diagnose the actual cause, fix it, then drive enough kilometres for the monitors to naturally revalidate before the test.

How much does a diagnostic cost at a garage vs. doing it yourself?

Most garages charge between €50 and €150 just to plug in their diagnostic tool and tell you the fault code — a service you can do yourself in a few minutes with a personal OBD2 scanner. A garage diagnostic still has value for interpreting complex codes or for deeper diagnostics beyond a simple reading (component testing, oscilloscope, precise electrical measurements), but for the first reading of a simple code, a personal scanner is more than enough and pays for itself the very first time you use it.

Engine light and insurance: what does the warranty cover?

If your vehicle is still under manufacturer warranty, an engine light linked to a manufacturing defect (rather than normal wear or a lack of maintenance) is generally covered free of charge by the manufacturer's network. Always keep your maintenance invoices: an incomplete service record can be grounds for refusing warranty cover in the event of a dispute.

FAQ — Engine light on

Can the engine light come on and then go off by itself?

Yes, particularly if the fuel cap wasn't closed properly or with an intermittent fault. The light can go off after a few start cycles if the control unit doesn't redetect the fault, but the code stays stored in memory and remains readable with an OBD2 scanner until it's manually cleared.

Can you drive for a long time with the engine light steadily on?

It's not advisable to wait too long even with a steady light: an untreated minor fault can develop into a more costly problem (a faulty oxygen sensor left unreplaced, for example, can eventually damage the catalytic converter).

Is the engine light only linked to the combustion engine?

On hybrid vehicles, the engine light (MIL) still relates to the combustion engine and its related systems. Faults specific to the high-voltage electrical side are generally flagged by a separate light specific to the manufacturer's hybrid system.