P2096Powertrain
Powertrain · SAE
Post-Catalyst Fuel Trim Too Lean (Bank 1)
Meaning
The fine fuel trim based on the downstream sensor (bank 1) tends too far lean. The ECU cannot keep the ideal ratio downstream, signalling a consistently fuel-poor condition.
Common causes
- Exhaust leak near the downstream sensor
- Intake air leak
- Inaccurate upstream or downstream O2 sensor
- Low fuel pressure or partially clogged injectors
- Degraded catalytic converter
Symptoms
- Check engine light on
- Slightly increased fuel consumption
- Idle not perfectly smooth
- Possible hesitation on acceleration
Severity
Mild/moderate: usually drivable, but indicates a wrong mixture or exhaust leak to be corrected.
What to do
- Inspect exhaust and manifold near the downstream sensor
- Look for intake air leaks
- Check fuel pressure and injector condition
- Check the upstream and downstream sensor values