P1157 – BMW DTC

BMW DTC P1157 – O2 Sensor Heater Circuit High Voltage (Bank 2 Sensor 2)

DTC P1157 meaning on BMW

The Diagnostic Trouble Code (DTC) P1157 for BMW indicates an issue with the O2 sensor heater circuit in Bank 2 Sensor 2. This code specifically points to a high voltage condition detected in the O2 sensor heater circuit of the downstream (post-catalytic converter) oxygen sensor on the second bank of cylinders in the engine.

BMW DTC P1157 symptoms

Symptoms of DTC P1157 on a BMW may include:

• Check Engine Light (CEL) illuminated on the dashboard
• Decreased fuel efficiency
• Engine running rough or misfiring
• Reduced engine performance

BMW DTC P1157 causes

The common causes of DTC P1157 on a BMW include:

• Faulty O2 sensor heater circuit
• Short circuit or open circuit in the O2 sensor heater wiring
• Defective O2 sensor heater relay
• Issues with the engine control module (ECM)

BMW DTC P1157 seriousness

While DTC P1157 may not cause immediate drivability issues, it is important to address this fault promptly. Ignoring this code can lead to decreased fuel efficiency, increased emissions, and potential damage to the catalytic converter over time.

How to diagnose DTC P1157 on BMW

To diagnose DTC P1157 on a BMW, you can follow these steps:

1. Use an OBD-II scanner to retrieve the fault code and verify the specific details of the code.
2. Inspect the wiring and connectors related to Bank 2 Sensor 2 O2 sensor heater circuit for any visible damage or corrosion.
3. Check the O2 sensor heater relay for proper operation.
4. Test the O2 sensor heater circuit for continuity and resistance.
5. Perform a thorough inspection of the O2 sensor itself for any signs of damage or malfunction.

How to fix DTC P1157 on BMW

To fix DTC P1157 on a BMW, you can consider the following steps:

1. Replace the faulty O2 sensor in Bank 2 Sensor 2.
2. Repair any damaged wiring or connectors in the O2 sensor heater circuit.
3. Replace the O2 sensor heater relay if necessary.
4. If the issue persists, consult a professional mechanic for further diagnosis and repair.

How to erase DTC P1157 on BMW

To erase DTC P1157 on a BMW, you can use an OBD-II scanner to clear the fault code from the engine control module’s memory. After addressing the underlying issue causing the fault code, clearing the code will reset the Check Engine Light and monitor the system for any recurring faults.

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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