What it means
The module detects that the reductant control module power relay de-energizes earlier than expected. It sets the code when relay operation does not match the expected timing during the relevant shutdown monitor.
How it works
The reductant control module power relay supplies power to the DEF control system and should switch off at the expected point during shutdown. This code sets when the module detects that the relay de-energizes too early, potentially interrupting the system’s expected shutdown sequence.
Common causes
Most likely first.
- Faulty reductant control module power relay
- Damaged relay wiring or connector
- Poor electrical connection or ground
- Reductant control module fault
- Low system voltage
Symptoms
- Check engine light
- AdBlue or reductant warning
- Reduced engine power
- Starting restriction warning
How to diagnose it
- Record freeze-frame data and any related voltage or reductant-module codes, then check whether low system voltage was present when the early shutdown was detected.
- Inspect the reductant control module relay and its socket for corrosion, heat damage, loose fit, or water intrusion.
- Check the relay wiring, connectors, power feed, and ground for damage or poor connections.
- Use a scan tool or meter to observe relay command and module supply during shutdown, following the manufacturer’s procedure.
- Test relay operation and the relevant circuits against the manufacturer’s specification.
- If the relay and wiring pass, check the reductant control module for a fault or applicable update using vehicle-specific service information.
Common fixes
- Clean and secure a loose or corroded relay connection.
- Repair damaged relay wiring, power feed, or ground.
- Replace a relay that fails its specified switching test.
- Correct a low-voltage issue affecting relay operation.
- Repair a confirmed reductant control module fault or apply an applicable update.
Can I keep driving?
If there are no drivability symptoms, a short trip may be possible, but arrange diagnosis soon because the DEF system may not shut down or operate as intended. Do not ignore a reductant or starting-restriction warning, which can progress to reduced power or a restart limit.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.