P21DD
Reductant Heater A Current Too Low
P21DD is an OBD-II diagnostic trouble code meaning: Reductant Heater A Current Too Low. Common causes: reagent heating element malfunction, open or short circuit in the heater circuit. Estimated repair cost: $56–167.
Symptoms
- Check engine light is on
- Reduced engine power
- SCR system malfunction message appears
- Increased fuel consumption
- Increased NOx emissions
Causes
- Reagent heating element malfunction
- Open or short circuit in the heater circuit
- Problems with the heater circuit relay or fuse
- Heater control module malfunction
- Poor contact in heater circuit connectors
How to Fix
- Check heater circuit fuse and relay
- Check the integrity of wiring and connectors
- Measure the resistance of the heating element
- Check the operation of the heater control module
- If necessary, replace the heating element or control module
Related codes
Error P21DD by Vehicle Brand
FAQ
What does the P21DD code mean?
P21DD is an OBD-II diagnostic trouble code that indicates: Reductant Heater A Current Too Low
What causes a P21DD error code?
The most common causes of P21DD include: Reagent heating element malfunction; Open or short circuit in the heater circuit; Problems with the heater circuit relay or fuse; Heater control module malfunction.
How do I fix a P21DD diagnostic trouble code?
To fix P21DD: Check heater circuit fuse and relay. Check the integrity of wiring and connectors. Measure the resistance of the heating element. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P21DD?
Limited driving only, diagnose soon
How much does it cost to fix P21DD?
The estimated repair cost for P21DD is $56–167. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat