OBD-II code · Powertrain (generic, extended)
P2177 System Too Lean Off Idle Bank 1
Fuel trim values on bank 1 indicate a lean condition during off-idle operation. The ECU has to add significant fuel correction to maintain stoichiometric mixture above idle.
Is it safe to drive with P2177?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyVacuum leak under load
- PossibleLow fuel pressure / weak pump
- PossibleContaminated MAF sensor
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Intake Manifold, Vacuum Hoses, Mass Air Flow Sensor, Fuel Pump, Fuel Injector
Related codes
- P2179System Too Lean Off Idle Bank 2
- P2174Throttle Actuator Control System - Sudden Low Air Flow Detected
- P2175Throttle Actuator Control System - Low Air Flow Detected
- P2176Throttle Actuator A Control System - Idle Position Not Learned
- P2178System Too Rich Off Idle Bank 1
- P217AFuel Injector Group G Supply Voltage Circuit/Open
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.