Vehicle
2010 BMW 1-Series 2.0L Petrol
Title
2AEC, Replaced NOx Sensor
Complaint
The customer states the check engine light is on.
Cause
Connected a scan tool and found code 2AEC – Nitrogen Oxide Sensor, Self-Diagnosis. Performed a road test, used the scan tool to monitor live data and found the NOx sensor signal parameter was erratic. Visually inspected the NOx sensor wiring harness and found no obvious signs of damage. Disconnected the NOx sensor connector, visually inspected the connector and terminals and found no obvious signs of damage. With the key on, engine off, used a multi-meter, checked for voltage and ground at the NOx sensor connector and found both were present. Backprobed the NOx sensor, ran the engine, monitored the sensor signal on a lab scope and found the NOx sensor signal observed on the lab scope intermittently dropped out. The results of these tests verified the NOx sensor was faulty.
Correction
Replaced the NOx sensor, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.