Engine and gearbox (P)
P2187: System Too Lean at Idle
The engine control unit has detected that the air-fuel mixture is too lean when the engine is idling. This means there is too much air or not enough fuel in the mixture.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Rough idle
- Engine stalling
- Poor fuel economy
- Check engine light on
Common causes
- Vacuum leak
- PCV fault
- Injector restriction
- Faulty oxygen sensor
- Fuel pressure issue
How to check it yourself
- Inspect for vacuum leaks
- Check PCV valve operation
- Examine fuel injectors
- Test oxygen sensors
- Measure fuel pressure
Can I keep driving?
The car can be driven, but prolonged driving with this issue may cause further damage.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer