All trouble codes → Rich fuel mixture codes
Rich fuel mixture codes
A “rich” code means the computer pulled fuel out to correct a mixture that read too rich, and hit its limit. Leaking injectors, high fuel pressure, a mass-air sensor over-reporting, or a purge valve dumping fuel vapour are the common causes. Left alone, a rich mixture wastes fuel and can overheat and ruin the catalytic converter.
Fuel mixture fault — fix soon to avoid catalyst damage and poor fuel economy.
Common causes
- Leaking injector(s)
- High fuel pressure / faulty regulator
- MAF over-reporting
- Fuel-saturated EVAP purge (purge valve stuck open)
- Oil diluted with fuel
First checks
- Compare trims at idle vs 2,500 rpm
- Pinch/disconnect the purge line and watch trims
- Check fuel pressure and injector leak-down
System: Fuel & air metering. This is general guidance for the generic OBD-II codes in this group; always confirm against the service information for your specific vehicle.
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