What are the common causes of P20C6?

A reductant heater D element that reads outside its expected range. Corrosion or damage in the heater D control circuit. A failed reductant heater control module. An ECM software fault skewing the heater D current reading.

Read the reductant heater D control circuit on a scan tool. Compare heater D current draw to the expected value. Test the heater D wiring and connector. Check for ECM software updates. Replace reductant heater D if current draw is out of range. Clear the code and retest.

P20C6

Reductant Heater D Control Circuit Performance

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

What it means

P20C6 means Reductant Heater D Control Circuit Performance.

Check these first

A reductant heater D element that reads outside its expected range
Corrosion or damage in the heater D control circuit
A failed reductant heater control module
An ECM software fault skewing the heater D current reading

What to do next

Read the reductant heater D control circuit on a scan tool
Compare heater D current draw to the expected value
Test the heater D wiring and connector
Check for ECM software updates
Replace reductant heater D if current draw is out of range
Clear the code and retest

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Updated

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