P2188System Too Rich at Idle (Bank 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2188 means the long-term fuel trim of bank 1 has to remove more fuel than allowed in the idle and low-load range, the additive part of the mixture adaptation on Bosch-type systems. GM's 2008 3.6 LLT sets it below -6.0 % at 520 to 1120 rpm and 1.7 to 7.8 g/s, with closed loop and coolant above 60 °C. On the Opel/GM 2.0 turbo in the Saab 9-5 (2010) the weighted long-term trim must stay below its limit for 4 s or 50 s in total (Type B); Saab's test gives -22 to 0 % as normal trim and 19 to 42 kPa manifold pressure at idle. At idle the extra fuel typically comes from sources the ECM does not meter: Mercedes lists for the M132 engine a leaking PCV valve, leaking injectors or excessive fuel pressure, wrong intake pressure readings, a restricted or worn throttle and a contaminated oxygen sensor. A saturated charcoal canister purging at idle has the same effect. Stellantis found an airflow straightener in the air box clipped in wrong, which disturbed the air mass reading and set P2188 and P2190.
- What you may notice
- Malfunction indicator lamp on
- Rough idle, fuel smell
- Likely causes
- PossibleLeaking injector or fuel pressure too high
- PossibleFuel vapour from the purge valve or oil-diluted crankcase gases
- PossibleAir mass or manifold pressure reading wrong
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.