P21CA: The AdBlue control unit power supply voltage has an electrical fault
The AdBlue control unit power supply voltage has an electrical fault. It may be the part itself, its connector or the wiring.
| Code | P21CA |
|---|---|
| System | Engine and transmission |
| Group | P21xx, Throttle, injection and emissions |
| Type | Generic: it means the same on every make |
How to read and clear P21CA with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P21CA with its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P21C3 The AdBlue heater relay control gives a lower signal than normal
- P21C4 The AdBlue heater relay control gives a higher signal than normal
- P21C5 The AdBlue level sensor A has got stuck
- P21C6 The AdBlue level sensor B has got stuck
- P21CB The AdBlue control unit power supply voltage is below normal
- P21CC The AdBlue control unit power supply voltage is above normal
- P21CD The AdBlue quality module power supply voltage is below normal
- P21CE The AdBlue quality module gives readings outside the normal range
- P2100 Throttle actuator A control motor circuit open
- P2101 Throttle actuator A control motor circuit range or performance
- P2102 Throttle actuator A control motor circuit low
- P2104 Throttle control system: forced idle
What does code P21CA mean?
The AdBlue control unit power supply voltage has an electrical fault. It may be the part itself, its connector or the wiring.
How do you clear P21CA?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P21CA comes back.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
