Engine warning light on? What a diagnostic test does (and doesn't) include
Published 04 Nov 2026 by Carwooshh
Last reviewed: 4 November 2026
A warning light means your car's computer has logged a fault code. A diagnostic test reads that code — it's the starting point, not the fix.
What's included: connecting a scanner, reading and interpreting fault codes, and often a short inspection to confirm the cause.
What usually isn't included: the repair itself. You'll get a diagnosis and a quote for the work. Some garages deduct the diagnostic fee if you go ahead with the repair there — ask.
Amber vs red: amber usually means get it checked soon; red or flashing usually means stop when safe, as continuing could cause damage.
FAQ
- Does a diagnostic test include the repair?
- Usually not. It identifies the fault and leads to a separate quote.
- Can I keep driving with the engine light on?
- If it's steady amber, drive gently and book a check. If it's flashing or red, stop when safe.
- Will clearing the code fix the problem?
- No — the light will return if the fault is still there.