P21CA
Reductant Control Module Supply Voltage Circuit
P21CA is an OBD-II diagnostic trouble code meaning: Reductant Control Module Supply Voltage Circuit. Common causes: open or short circuit in the module power supply circuit, faulty relay or fuse. Estimated repair cost: $56–278.
Symptoms
- Check Engine light comes on
- Reducing engine power (limp mode)
- Increased fuel consumption
- SCR/AdBlue system error message on the dashboard
- Unpleasant exhaust smell
Causes
- Open or short circuit in the module power supply circuit
- Faulty relay or fuse
- Problems with wiring harness or contacts
- Malfunction of the reducer control module itself
- Circuit Grounding Problems
How to Fix
- Check the condition of fuses and relays
- Inspect the wiring harness for damage
- Check the voltage at the module terminals
- Test circuit integrity and grounding quality
- If necessary, replace the reducer control module
Related codes
Error P21CA by Vehicle Brand
FAQ
What does the P21CA code mean?
P21CA is an OBD-II diagnostic trouble code that indicates: Reductant Control Module Supply Voltage Circuit
What causes a P21CA error code?
The most common causes of P21CA include: Open or short circuit in the module power supply circuit; Faulty relay or fuse; Problems with wiring harness or contacts; Malfunction of the reducer control module itself.
How do I fix a P21CA diagnostic trouble code?
To fix P21CA: Check the condition of fuses and relays. Inspect the wiring harness for damage. Check the voltage at the module terminals. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21CA?
Yes, but get it checked soon
How much does it cost to fix P21CA?
The estimated repair cost for P21CA is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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