Volkswagen Audi Error Code P1138: How to Fix It

Q: Can I drive with error code P1138?

It's not recommended. Driving with a lean condition can cause poor performance, reduced fuel economy, and potential engine damage over time.

Q: What does 'too lean bank 2' mean?

It means the engine's bank 2 (the side not containing cylinder 1) is running with too much air or too little fuel, causing an imbalance in the air-fuel mixture.

Q: Will cleaning the MAF sensor fix P1138?

Yes, if the MAF sensor is dirty, cleaning it can resolve the code. However, if the sensor is faulty, replacement is needed.

Q: What tools do I need to diagnose P1138?

You'll need an OBD2 scanner to read codes and live data, and possibly a smoke machine for vacuum leaks, a fuel pressure gauge, and a multimeter.

Q: Can a bad oxygen sensor cause P1138?

Yes, a faulty oxygen sensor can send incorrect readings, leading to a lean fuel trim condition.

Abstract

Error code P1138 in Volkswagen or Audi vehicles indicates that the engine control module (ECM) has detected the long-term fuel trim for bank 2 is too lean, meaning the air-fuel mixture has too much air relative to fuel. This is often due to vacuum leaks, faulty mass airflow (MAF) sensor, or fuel system issues. Ignoring this code can lead to poor performance and potential engine damage.