What are the common causes of P20B1?

An open in the reductant heater coolant control valve circuit. A failed reductant heater coolant control valve. A backed out pin at the coolant control valve connector. Chafed wiring along the coolant control valve harness.

Command the reductant heater coolant control valve with a scan tool. Test the coolant control valve circuit for an open. Check the coolant control valve connector pins. Test the coolant control valve coil for an open. Replace the reductant heater coolant control valve if faulty. Clear the code and retest.

P20B1

Reductant Heater Coolant Control Valve Circuit/Open

System: Fuel and air metering (P code)
Lamp: Check Engine Light
Category: Powertrain - Fuel/Air Metering

What it means

P20B1 means Reductant Heater Coolant Control Valve Circuit/Open.

Where it lives

For P20B1, the valve sits on the circuit this code reports. The description of P20B1 reports the valve as open.

Check these first

An open in the reductant heater coolant control valve circuit
A failed reductant heater coolant control valve
A backed out pin at the coolant control valve connector
Chafed wiring along the coolant control valve harness

What to do next

Command the reductant heater coolant control valve with a scan tool
Test the coolant control valve circuit for an open
Check the coolant control valve connector pins
Test the coolant control valve coil for an open
Replace the reductant heater coolant control valve if faulty
Clear the code and retest

Look up another code

Code or symptom

Enter a full code or a symptom. Press / to search. How to read a code

Type a code above, or start from a symptom or a common code.

Updated

Generic SAE J2012 definition. Last updated 2026-10-10.