P20B5 – BMW DTC

BMW DTC P20B5 – Reductant Metering Unit Heater Control Circuit/Open

DTC P20B5 meaning on BMW

DTC P20B5 on a BMW indicates a fault with the Reductant Metering Unit Heater Control Circuit/Open. This fault code is related to the heating element control circuit of the reductant metering unit, which is a component of the Selective Catalytic Reduction (SCR) system used to reduce emissions in diesel engines.

BMW DTC P20B5 symptoms

Symptoms of DTC P20B5 on a BMW may include:

• Check Engine Light (MIL) illuminated
• Reduced engine performance
• Possible DEF (Diesel Exhaust Fluid) system warnings

BMW DTC P20B5 causes

Common causes of DTC P20B5 on a BMW include:

• Faulty reductant metering unit heater
• Open or short circuit in the heater control circuit
• Corrosion or poor connections in the wiring harness

BMW DTC P20B5 seriousness

DTC P20B5 should be addressed promptly as it can lead to increased emissions and potential compliance issues with emissions regulations. Ignoring this fault code may also result in reduced engine efficiency and performance.

How to diagnose DTC P20B5 on BMW

To diagnose DTC P20B5 on a BMW, you can perform the following steps:

1. Use a diagnostic scanner to retrieve the fault code and freeze frame data
2. Inspect the reductant metering unit heater and its wiring for any visible damage or corrosion
3. Check the resistance of the heater element to determine if it is within specifications
4. Test the continuity of the heater control circuit

How to fix DTC P20B5 on BMW

To fix DTC P20B5 on a BMW, you may need to:

1. Replace the faulty reductant metering unit heater
2. Repair any open or short circuits in the heater control circuit
3. Clean or repair any corroded connectors or wiring in the system
4. Clear the fault code and perform a test drive to ensure the issue is resolved

How to erase DTC P20B5 on BMW

To erase DTC P20B5 on a BMW, you can:

1. Use a diagnostic scanner to clear the fault code
2. Perform a battery reset by disconnecting the negative terminal for a few minutes
3. After clearing the code, ensure the issue has been resolved by monitoring the system for any reoccurrence

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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