P2098
Post Catalyst Fuel Trim System Too Lean (Bank 2)
Moderate· Fix soonIntermediatePowertrainGeneric, all makes
What it means
The ECU uses the downstream (after-catalyst) oxygen sensor to make small corrections to the fuel mixture. On bank 2 it has reached its limit while correcting a lean condition after the catalytic converter.
Is it safe to drive?
Usually safe to drive. Fix to avoid failing emissions and to protect the catalytic converter.
Symptoms
- Check engine light on
- Usually no noticeable driving symptoms
- Failed emissions test
Probable causes
Most likely first
- 1Exhaust leak near the downstream O2 sensor
- 2Upstream O2 or air/fuel sensor biased rich
- 3Failing downstream O2 sensor
- 4Small vacuum leak
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Check for exhaust leaks around both oxygen sensors and the converter.
- 3Compare upstream and downstream sensor readings on live data.
- 4Check overall fuel trims for a real lean or rich condition.
- 5Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Repair exhaust leaks
- Replace the upstream air/fuel sensor
- Replace the downstream O2 sensor
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.