Post Catalyst Fuel Trim System Too Lean - Bank 2

This code means the engine is running with too much air compared to fuel after the catalytic converter on bank 2.

The engine control module (ECM) monitors the exhaust gases after the catalytic converter through the oxygen sensor. The signal from the sensor indicates a lean mixture (more air, less fuel) when the voltage is lower than 0.45V under load conditions.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Check for any vacuum or exhaust leaks around bank 2. Use smoke test if necessary.
2. 22. Inspect the connections and condition of the post-catalytic converter O2 sensor. Check for corrosion or damage.
3. 33. Measure the voltage output of the post-catalytic O2 sensor while the engine is running. It should fluctuate between 0.6V to 0.9V.
4. 44. Check fuel pressure and ensure it is within specs (usually around 30-50 PSI depending on the vehicle).
5. 55. If all previous checks pass, consider replacing the post-catalytic converter O2 sensor.

• Vacuum leaks in intake or exhaust system
• Faulty post-catalytic converter O2 sensor
• Exhaust leaks before or near the O2 sensor
• Fuel delivery issues (low fuel pressure, clogged fuel filter)
• Engine control module (ECM) faults

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