What are the common causes of P20BD?

An open in the reductant heater B control circuit. A backed out pin at the reductant heater B connector. A failed reductant heater B element. A failed reductant heater control module.

Read the reductant heater B control circuit on a scan tool. Test the heater B control circuit for an open. Check the heater B connector pins. Measure reductant heater B resistance. Replace reductant heater B if the circuit tests good. Clear the code and retest.

P20BD

Reductant Heater B Control Circuit/Open

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

What it means

P20BD means Reductant Heater B Control Circuit/Open.

Check these first

An open in the reductant heater B control circuit
A backed out pin at the reductant heater B connector
A failed reductant heater B element
A failed reductant heater control module

What to do next

Read the reductant heater B control circuit on a scan tool
Test the heater B control circuit for an open
Check the heater B connector pins
Measure reductant heater B resistance
Replace reductant heater B if the circuit tests good
Clear the code and retest

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Updated

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