Question 1

What does a check engine light mean?

Accepted Answer

The check engine light (engine management light) means your car’s ECU has detected a fault and stored a diagnostic trouble code. It does not tell you what is wrong on its own — you need an OBD-II scanner to read the specific fault code. AI-Diagnostics-Pro then interprets that code and gives you a full UK-specific diagnostic report.

Question 2

Is it safe to drive with a check engine light on?

Accepted Answer

If the light is flashing, stop driving immediately — a flashing light usually indicates a serious engine misfire that can cause rapid catalytic converter damage. If the light is solid and steady, it is generally safe to drive short distances, but you should scan the code as soon as possible to understand the risk.

Question 3

How much does a car diagnostic cost at a garage?

Accepted Answer

Most UK garages charge between £40 and £120 just to plug in their diagnostic machine and read the codes. AI-Diagnostics-Pro gives you a full AI-generated diagnostic report specific to your vehicle for just £1.59 — a fraction of the cost, available instantly without a garage visit.

Question 4

Do OBD2 fault codes work on all cars?

Accepted Answer

They work on OBD-II compatible cars. In the UK that generally means petrol cars from 2001 and diesel cars from 2004 onwards, plus many late-1990s vehicles. Once a car is OBD-II compatible, the standard format is shared across manufacturers, but some fault codes are still manufacturer-specific.

Question 5

Can I clear a fault code myself?

Accepted Answer

You can clear a fault code using an OBD-II scanner, but if the underlying fault has not been fixed, the code will return within a few drive cycles. Clearing codes before an MOT test without fixing the fault is not recommended — the code will reappear and the MIL will illuminate, failing the test. Always fix the fault first.

Question 6

What is the most common OBD2 fault code in the UK?

Accepted Answer

P0420 (Catalyst System Efficiency Below Threshold) is one of the most common fault codes seen in UK garages. It indicates the catalytic converter is not operating efficiently. Before replacing the catalytic converter (which can cost £400–£800), it is worth checking the oxygen sensors first — a faulty O2 sensor is a cheaper fix that often triggers the same code.

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