What are the common causes of P20BA?

An open or short in the reductant heater A control circuit. A failed reductant heater A element. Corrosion or damage at the reductant heater A connector. A weak battery that drops supply voltage during a heater run.

Read the reductant heater A control circuit on a scan tool. Test reductant heater A element resistance and compare it to spec. Check the heater A connector and wiring for corrosion or damage. Check battery voltage and charging system output. Replace reductant heater A if resistance is out of range. Clear the code and retest.

P20BA

Reductant Heater A Control Circuit Performance

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

What it means

P20BA means Reductant Heater A Control Circuit Performance.

Check these first

An open or short in the reductant heater A control circuit
A failed reductant heater A element
Corrosion or damage at the reductant heater A connector
A weak battery that drops supply voltage during a heater run

What to do next

Read the reductant heater A control circuit on a scan tool
Test reductant heater A element resistance and compare it to spec
Check the heater A connector and wiring for corrosion or damage
Check battery voltage and charging system output
Replace reductant heater A if resistance is out of range
Clear the code and retest

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Updated

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