Question

2013 GMC Denali LML Duramax 2500HD 6.6L with engine code P20B9

Answer 1

The P20b9 code will be set when the Engine Control Module (ECM) indicates the reductant tank heater control circuit is open for greater than 4 s.

Possible Causes:

• Faulty Reductant Heater
• Reductant Heater harness is open or shorted
• Reductant Heater circuit poor electrical connection
• Faulty Reductant Pump and Sensor Assembly
• Faulty Reductant Control Module

P20B9 GMC Code - Reductant Heater 1 Control Circuit
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