The P20BC: Reductant Heater ‘A’ Control Circuit High refers to a condition where the voltage in the control circuit for reductant heater ‘A’ is higher than expected. This could indicate an electrical issue, such as excessive voltage supply to the heater, or problems with the heater itself or the control module.
P20BC – Quick Overview
Code | Information |
---|---|
Meaning | P20BC: Reductant Heater ‘A’ Control Circuit High |
Is it serious? | Yes, this can cause improper operation of the reductant heater, which is essential for emissions control. |
Possible causes | – High voltage in the reductant heater ‘A’ control circuit – Faulty heater – Faulty control module |
How to diagnose? | – Measure voltage in the heater control circuit – Test reductant heater ‘A’ – Check the control module functionality |
P20BC Meaning
The P20BC fault code indicates that the control circuit for reductant heater ‘A’ is experiencing a high voltage condition. This can cause the heater to malfunction, affecting the vehicle’s ability to manage emissions effectively. The issue could be due to electrical faults, a malfunctioning heater, or a problem with the control module responsible for regulating the heater.
Step-by-step diagnostic guide
Action | Description | Tools Needed |
---|---|---|
Check for Other Codes | Use an OBD-II scanner to check for any related codes that may provide additional information about the problem. | OBD-II Scanner |
Measure Voltage in the Heater Control Circuit | Use a multimeter to measure the voltage in the control circuit for reductant heater ‘A’. Ensure the voltage is within the manufacturer’s specifications. | Multimeter |
Test Reductant Heater ‘A’ | Test the functionality of reductant heater ‘A’ using a diagnostic tool to ensure it is not drawing too much power. | Multimeter, Diagnostic Tool |
Inspect the Control Module | Check the control module to ensure it is functioning properly and not supplying excessive voltage to the heater. | Diagnostic Tool |
Repair or Replace Wiring/Heater | If high voltage is detected, inspect the wiring for faults and repair or replace reductant heater ‘A’ if needed. | Wiring Kit, Replacement Heater |
Clear the Code and Test Drive | After making repairs, clear the code with 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 P20BC code does not return. | OBD-II Scanner |

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