Fix P20C7: STEP-BY-STEP diagnostic GUIDE!

The P20C7: Reductant Heater ‘D’ Control Circuit Low refers to a low voltage condition in the control circuit for reductant heater ‘D’. This can result in the heater not functioning properly, which could affect the vehicle’s emissions control system.

P20C7 – Quick Overview

CodeInformation
MeaningP20C7: Reductant Heater ‘D’ Control Circuit Low
Is it serious?Yes, this can lead to the reductant heater not functioning properly, affecting emissions control.
Possible causes– Low voltage in the reductant heater ‘D’ control circuit
– Faulty heater
– Faulty control module
How to diagnose?– Measure voltage in the heater control circuit
– Test reductant heater ‘D’
– Check the control module functionality

P20C7 Meaning

The P20C7 fault code indicates that the voltage in the control circuit for reductant heater ‘D’ is lower than expected. This low voltage condition may cause the heater to malfunction, potentially leading to emissions-related issues. The problem could be due to faulty wiring, a malfunctioning heater, or an issue with the control module responsible for regulating the heater.

Step-by-step diagnostic guide

ActionDescriptionTools Needed
Check for Other CodesUse an OBD-II scanner to check for additional related codes that may provide more information.OBD-II Scanner
Measure Voltage in the Heater Control CircuitUse a multimeter to measure the voltage in the control circuit for reductant heater ‘D’ to confirm it is within the manufacturer’s specifications.Multimeter
Test Reductant Heater ‘D’Use a diagnostic tool to test the functionality of reductant heater ‘D’ to ensure it is operating correctly under the current voltage.Diagnostic Tool, Multimeter
Check the Control ModuleVerify that the control module is functioning properly and not causing the low voltage issue.Diagnostic Tool
Repair or Replace Wiring/HeaterIf low voltage is detected, inspect the wiring for faults, shorts, or disconnections, and repair or replace the heater as necessary.Wiring Kit, Replacement Heater
Clear the Code and Test DriveAfter making repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to confirm the problem is resolved.OBD-II Scanner, Vehicle Manual
Recheck for CodesAfter the test drive, rescan the vehicle to ensure the P20C7 code does not return.OBD-II Scanner
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