P20B9 – BMW DTC

BMW DTC P20B9 – Reductant Heater ‘A’ Control Circuit/Open

DTC P20B9 meaning on BMW

DTC P20B9 is a diagnostic trouble code that indicates an issue with the Reductant Heater ‘A’ Control Circuit/Open in a BMW vehicle. The reductant heater is responsible for heating the diesel exhaust fluid (DEF) to optimize its performance in reducing emissions.

BMW DTC P20B9 symptoms

Symptoms of DTC P20B9 in a BMW may include:

• Check Engine Light illuminated
• Reduced engine performance
• Increased fuel consumption
• Possible DEF freezing in cold weather

BMW DTC P20B9 causes

Common causes of DTC P20B9 in a BMW include:

• Faulty reductant heater ‘A’
• Open or short circuit in the heater control circuit
• Defective reductant heater control module
• Wiring issues or poor connections

BMW DTC P20B9 seriousness

DTC P20B9 should not be ignored as it can lead to increased emissions and potential engine performance issues. It is important to address this code promptly to ensure proper vehicle operation and compliance with emissions regulations.

How to diagnose DTC P20B9 on BMW

To diagnose DTC P20B9 on a BMW, you can follow these steps:

1. Use a diagnostic scanner to retrieve the fault codes
2. Inspect the reductant heater ‘A’ and its wiring for any visible damage
3. Check the resistance of the reductant heater to determine if it is faulty
4. Test the reductant heater control module for proper operation
5. Verify the integrity of the control circuit by checking for continuity and shorts

How to fix DTC P20B9 on BMW

To fix DTC P20B9 on a BMW, you may need to:

1. Replace the faulty reductant heater ‘A’
2. Repair any open or short circuits in the heater control circuit
3. Replace the defective reductant heater control module
4. Repair any wiring issues or poor connections

How to erase DTC P20B9 on BMW

To erase DTC P20B9 on a BMW, you can:

1. Use a diagnostic scanner to clear the fault codes
2. After making the necessary repairs, perform a test drive to ensure the code does not return

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

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.