P2188
System Too Rich at Idle (Bank 1)
Fuel trim on bank 1 hits the rich limit only at idle. Often a leaking injector dribbling fuel at low load, a sticky purge valve dumping fuel vapour, or fuel pressure regulator that fails to relieve pressure when intake vacuum is high.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Black smoke from exhaust on acceleration
- Smell of unburned fuel, fouled spark plugs
Common causes
Ordered by how often each turns out to be the cause.
- Leaking injector at idleCommon
- Purge valve stuck openPossible
Parts involved
- Fuel Injector
- EVAP Purge Valve
- Fuel Pressure Regulator
P2188 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.