P0151 Fault on 2003 Mercedes ML350 - O2 Sensor Issue and Symptoms
Hello everyone, My 2003 Mercedes ML350 has started exhibiting unusual behavior about two weeks ago. I was initially advised to replace the Air Flow Meter, which I did — the car ran smoothly for three days before the issue returned. After scanning the system today, I'm now seeing a P0151 diagnostic trouble code. I've already checked the O2 sensors on Bank 2 and confirmed they are functioning properly. My technician also cleaned the O2 sensor using carburetor cleaner with no improvement. The car still exhibits a noticeable loss of power when slowing down at intersections and attempting to accelerate again. This symptom is quite concerning, especially since the P0151 code points to an issue with the oxygen sensor circuit or sensor on Bank 2. I'm seeking advice on what the next troubleshooting steps should be — any insights into possible causes or diagnostic procedures would be greatly appreciated. Thank you in advance for your help! P.S. The vehicle is a 2003 Mercedes ML350 with a known history of emission-related issues.
P0151 indicates an oxygen sensor circuit or sensor fault on Bank 2. This code should be investigated further — check for wiring harness damage, ground connections, and ensure the sensor is properly seated. Also verify that the vehicle's ECU has accurate data from the sensor. If the O2 sensor appears functional but still triggers P0151, consider replacing it as a next step.