BMW DTC P20B4 – Reductant Heater Coolant Control Valve Circuit High
DTC P20B4 meaning on BMW
DTC P20B4 on a BMW indicates a fault with the Reductant Heater Coolant Control Valve Circuit being detected as high. This fault code is related to the system that controls the heating of the diesel exhaust fluid (DEF) or AdBlue solution in the Selective Catalytic Reduction (SCR) system.
BMW DTC P20B4 symptoms
Symptoms of DTC P20B4 on a BMW may include the check engine light being illuminated on the dashboard. In some cases, the vehicle may go into a reduced power mode to protect the engine and emissions system.
BMW DTC P20B4 causes
The most common causes of DTC P20B4 on a BMW are a faulty Reductant Heater Coolant Control Valve, wiring issues in the circuit, or a problem with the engine control module (ECM) that monitors the system.
BMW DTC P20B4 seriousness
While DTC P20B4 may not cause immediate drivability issues, it is important to address this fault code promptly to prevent potential damage to the emissions system and ensure the vehicle meets emissions standards.
How to diagnose DTC P20B4 on BMW
To diagnose DTC P20B4 on a BMW, a mechanic would typically use a diagnostic scanner to retrieve the fault code and perform a visual inspection of the Reductant Heater Coolant Control Valve and its wiring. They may also conduct tests to check the functionality of the valve and related components.
How to fix DTC P20B4 on BMW
Fixing DTC P20B4 on a BMW usually involves replacing the faulty Reductant Heater Coolant Control Valve or repairing any damaged wiring in the circuit. It is important to follow the manufacturer’s repair procedures and use quality replacement parts to ensure proper functionality.
How to erase DTC P20B4 on BMW
Once the underlying issue causing DTC P20B4 on a BMW has been resolved, the fault code can be cleared using a diagnostic scanner. This will reset the check engine light and allow the vehicle’s ECM to monitor the system for any new 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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