P21C2
Reductant Heater Relay Control Circuit/Open
P21C2 is an OBD-II diagnostic trouble code meaning: Reductant Heater Relay Control Circuit/Open. Common causes: open or short circuit in wiring harness, faulty heater relay. Estimated repair cost: $17–89.
Symptoms
- Check Engine Light Is On
- Possible reduction in engine power
- Increased NOx emissions
- SCR system error message on instrument panel
- Problems starting in cold weather (if the reagent is frozen)
Causes
- Open or short circuit in wiring harness
- Faulty heater relay
- Damage to connectors or corrosion of contacts
- Problems with the SCR control unit
- Malfunction of the heating element itself
How to Fix
- Check the integrity of the wiring harness to the heater relay
- Check the resistance and operation of the relay
- Inspect connectors for corrosion or damage
- Check power and ground in the control circuit
- If necessary, replace the relay or heating element
Related codes
Error P21C2 by Vehicle Brand
FAQ
What does the P21C2 code mean?
P21C2 is an OBD-II diagnostic trouble code that indicates: Reductant Heater Relay Control Circuit/Open
What causes a P21C2 error code?
The most common causes of P21C2 include: Open or short circuit in wiring harness; Faulty heater relay; Damage to connectors or corrosion of contacts; Problems with the SCR control unit.
How do I fix a P21C2 diagnostic trouble code?
To fix P21C2: Check the integrity of the wiring harness to the heater relay. Check the resistance and operation of the relay. Inspect connectors for corrosion or damage. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21C2?
Yes, but get it checked soon
How much does it cost to fix P21C2?
The estimated repair cost for P21C2 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
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