P21CD
Reductant Quality Module Supply Voltage Low
P21CD is an OBD-II diagnostic trouble code meaning: Reductant Quality Module Supply Voltage Low. Common causes: problems with wiring to the reagent quality module, faulty relay or module power fuse. Estimated repair cost: $56–278.
Symptoms
- Check Engine light comes on
- Reduced engine power
- Possible SCR error messages
- Increased consumption of AdBlue reagent
- Problems starting the engine in cold weather
Causes
- Problems with wiring to the reagent quality module
- Faulty relay or module power fuse
- Short circuit in the module circuit
- Malfunction of the reagent quality module itself
- Module grounding problems
How to Fix
- Check fuses and relays of the module power supply circuit
- Diagnose the condition of wiring and connectors
- Check the supply voltage on the module
- Test ground circuit resistance
- If necessary, replace the reagent quality module
Related codes
Error P21CD by Vehicle Brand
FAQ
What does the P21CD code mean?
P21CD is an OBD-II diagnostic trouble code that indicates: Reductant Quality Module Supply Voltage Low
What causes a P21CD error code?
The most common causes of P21CD include: Problems with wiring to the reagent quality module; Faulty relay or module power fuse; Short circuit in the module circuit; Malfunction of the reagent quality module itself.
How do I fix a P21CD diagnostic trouble code?
To fix P21CD: Check fuses and relays of the module power supply circuit. Diagnose the condition of wiring and connectors. Check the supply voltage on the module. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21CD?
Yes, but get it checked soon
How much does it cost to fix P21CD?
The estimated repair cost for P21CD is $56–278. Actual cost depends on your vehicle, location, and labor rates.
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