P2096 — Post Catalyst Fuel Trim System Too Lean (Bank 1)
Long-term fuel trim derived from the downstream oxygen sensor on bank 1 has reached the lean limit. The downstream-trim correction is a fine adjustment that runs after the main trim from the upstream sensor; persistent excursion suggests a degraded catalyst, an exhaust leak after the catalyst, or a drifting downstream sensor.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Oxygen sensor downstream
- Catalytic converter
- Exhaust pipe post cat
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- Exhaust leak after catalyst (post-cat sensor sees ambient air)
- Downstream sensor drifting
- Catalyst lightly degraded
Possible symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.