The P20C3: Reductant Heater ‘C’ Control Circuit Low refers to a condition where the control circuit for reductant heater ‘C’ is experiencing a lower-than-expected voltage. This could result in the heater failing to function correctly, which may lead to problems in the emissions control system.
P20C3 – Quick Overview
Code | Information |
---|---|
Meaning | P20C3: Reductant Heater ‘C’ Control Circuit Low |
Is it serious? | Yes, this may cause the reductant heater ‘C’ to fail, affecting emissions control and vehicle performance. |
Possible causes | – Low voltage in the reductant heater ‘C’ control circuit – Faulty heater – Faulty control module |
How to diagnose? | – Measure voltage in the heater control circuit – Test reductant heater ‘C’ – Check the control module functionality |
P20C3 Meaning
The P20C3 fault code signals that the control circuit for reductant heater ‘C’ is experiencing low voltage. This can cause the heater to underperform or fail, potentially leading to improper functioning of the vehicle’s emissions control system. Common causes include faulty wiring, a failing heater, or issues with the control module that governs the heater.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for any additional codes that might help diagnose the low voltage 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 ‘C’ to ensure it is within the manufacturer’s specified range. | Multimeter |
Test Reductant Heater ‘C’ | Test the performance of reductant heater ‘C’ using a diagnostic tool to determine if it is functioning correctly under the current voltage. | Diagnostic Tool, Multimeter |
Inspect the Control Module | Check the control module for any faults that could be causing the low voltage condition in the control circuit. | Diagnostic Tool |
Repair or Replace Wiring/Heater | If low voltage is detected, inspect the wiring for shorts, breaks, or disconnections 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 test drive the vehicle to confirm the issue is resolved. | OBD-II Scanner, Vehicle Manual |
Recheck for Codes | After the test drive, rescan the vehicle to ensure the P20C3 code does not return. | OBD-II Scanner |

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