The P20C8: Reductant Heater ‘D’ Control Circuit High refers to a condition where the control circuit for reductant heater ‘D’ is experiencing a higher-than-expected voltage. This excessive voltage could lead to improper functioning of the heater, affecting the vehicle’s emissions control system.
P20C8 – Quick Overview
| Code | Information |
|---|---|
| Meaning | P20C8: Reductant Heater ‘D’ Control Circuit High |
| Is it serious? | Yes, this can cause the heater to malfunction, leading to emissions system inefficiencies. |
| Possible causes | – High 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 |
P20C8 Meaning
The P20C8 fault code signals that the voltage in the control circuit for reductant heater ‘D’ is higher than expected. This could cause the heater to fail or operate improperly, leading to potential issues with the vehicle’s emissions system. The problem could be due to an electrical issue, a defective heater, or a malfunctioning control module.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for additional codes that may offer more details about the issue. | OBD-II Scanner |
| Measure Voltage in the Heater Control Circuit | Use a multimeter to measure the voltage in the control circuit for reductant heater ‘D’ and ensure it is within the manufacturer’s specified range. | Multimeter |
| Test Reductant Heater ‘D’ | Test the functionality of reductant heater ‘D’ using a diagnostic tool to verify that it is not being damaged by the excessive voltage. | Multimeter, Diagnostic Tool |
| Check the Control Module | Verify that the control module is working correctly and not sending too much voltage to heater ‘D’. | Diagnostic Tool |
| Repair or Replace Wiring/Heater | If high voltage is detected, inspect the wiring for damage or excessive voltage supply, and repair or replace the heater as necessary. | Wiring Kit, Replacement Heater |
| Clear the Code and Test Drive | After performing repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to ensure the problem is resolved. | OBD-II Scanner, Vehicle Manual |
| Recheck for Codes | After the test drive, rescan the vehicle to ensure the P20C8 code does not return. | OBD-II Scanner |
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