BMW DTC P0166 – O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
DTC P0166 meaning on BMW
The Diagnostic Trouble Code (DTC) P0166 for BMW indicates that there is no activity detected in the O2 sensor circuit of Bank 2 Sensor 3. This means that the O2 sensor located in the third position on Bank 2 of the engine is not sending any signals or data to the engine control module (ECM).
BMW DTC P0166 symptoms
Symptoms of DTC P0166 on a BMW may include poor fuel economy, rough idling, engine misfires, hesitation during acceleration, and an illuminated Check Engine Light on the dashboard.
BMW DTC P0166 causes
The causes of DTC P0166 on a BMW can vary, but common reasons include a faulty O2 sensor, damaged wiring or connectors in the sensor circuit, a blown fuse related to the sensor, or issues with the ECM.
BMW DTC P0166 seriousness
While DTC P0166 may not cause immediate drivability issues, it can lead to poor engine performance and increased emissions. Ignoring this fault code can result in long-term damage to the engine and catalytic converter.
How to diagnose DTC P0166 on BMW
To diagnose DTC P0166 on a BMW, start by visually inspecting the O2 sensor and its wiring for any visible damage. Use a multimeter to test the sensor’s voltage output and resistance. Check for any blown fuses related to the sensor circuit. Additionally, scan the ECM for any other related fault codes.
How to fix DTC P0166 on BMW
To fix DTC P0166 on a BMW, start by replacing the faulty O2 sensor in Bank 2 Sensor 3. Ensure all wiring and connectors are in good condition and make any necessary repairs. Clear the fault code from the ECM using a diagnostic scanner after completing the repairs.
How to erase DTC P0166 on BMW
To erase DTC P0166 on a BMW, use a diagnostic scanner to access the ECM and clear the fault code. After making the necessary repairs and ensuring the issue is resolved, reset the ECM to remove the fault code from the system.
Recommended tools & DTC Scanners for BMW
Best Diagnostic App for modern BMWs: BimmerLink
Recommended Bluetooth adapter for Bimmerlink: OBDLink CX
Cable adapter for Bimmerlink: Enet Cable USB Type C
For older BMWs we recommend: Autel AutoLink AL319 (2024 version)
Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter
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