Diagnostic report · 2021 BMW 330i
Check Engine Light
Engine management system reported an abnormal condition after refuelling.
Safe to drive — with caution
You can likely continue driving, but schedule a diagnostic check soon.
Explanation
What this means
Your engine management system detected an abnormal condition. It compares the air and fuel entering the engine with what leaves it — when those numbers stop matching, the warning light is switched on so the condition can be checked before it affects other components.
Based on the information provided, the most likely causes are:
Loose or damaged fuel cap
74%- Low — evaporative system leak, no mechanical damage
- €0–€35
Impact
Estimated repair
Oxygen sensor issue
68%- Medium — higher fuel use, possible catalytic converter wear
- €180–€420
Impact
Estimated repair
Air/fuel mixture problem
41%- Medium — rough idle and reduced throttle response
- €90–€320
Impact
Estimated repair
Action plan
What to do next
Work through these in order. Stop and seek professional help if anything feels unsafe.
- 01
Check the fuel cap.
Remove the cap, inspect the rubber seal for cracks or debris, then refit it until it clicks at least three times.
2 minEasy - 02
Restart the vehicle and monitor the warning light.
Some systems need several drive cycles before the light clears on its own. Note whether the light is steady or flashing.
5 minEasy - 03
If the warning remains, scan the OBD-II system.
Read stored fault codes and short/long term fuel trim values. Trims above +10% point towards a lean condition.
10 minModerate
Ask the AI mechanic
AI guidance is informational and does not replace a professional inspection.