P2189System Too Lean at Idle (Bank 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2189 is the bank 2 version of P2187: on engines with a front oxygen sensor per bank, the long-term trim of bank 2 has to add more fuel than allowed at idle and low load. GM's 2005 2.8 and 3.6 V6 set it when the additive correction exceeds 7 %, the 2008 3.6 LLT above 6.1 % at 520 to 1120 rpm, airflow of 1.7 to 7.8 g/s, engine load of 11 to 45 % and coolant above 60 °C, and GM's 2024 tables above about 5.5 % over two trips. Because both banks share the throttle, crankcase ventilation and brake booster vacuum, a leak there normally lifts the idle trim on both banks, setting P2187 and P2189 together. A code on bank 2 alone points to something only that bank sees: an intake manifold gasket or runner leak on that side, an injector on that bank, or the bank 2 front sensor or its wiring. Comparing both banks' trims at idle and at 2500 rpm narrows it down.
- What you may notice
- Malfunction indicator lamp on
- Rough or hunting idle
- Likely causes
- PossibleIntake gasket or runner leak on the bank 2 side
- PossibleShared vacuum leak, usually with P2187 present too
- RareBank 2 front sensor, its wiring or an injector on that bank
- 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: €10 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.