What it means
The module detects that the reductant control module power relay de-energizes later 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 should remove power at a defined point during vehicle shutdown. This code sets when the relay de-energizes later than the module expects, which can result from a sticking relay, a circuit fault, low voltage, or a control-module problem.
Common causes
Most likely first.
- Faulty reductant control module power relay
- Damaged relay wiring or connector
- Relay sticking or slow to release
- 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
- Review freeze-frame data and related voltage codes to see whether low system voltage coincided with the late relay release.
- Inspect the reductant module power relay and socket for heat damage, corrosion, contamination, or a relay that does not seat firmly.
- Check relay wiring and connectors for damage, poor contact, or a weak ground.
- Observe relay command and module power during shutdown with a scan tool or meter, using the manufacturer’s procedure.
- Test whether the relay releases correctly and verify the circuit against the manufacturer’s specification.
- If the relay and circuits pass, use vehicle-specific service information to investigate the reductant control module.
Common fixes
- Repair a poor relay socket connection or corroded terminal.
- Repair damaged relay wiring or ground connections.
- Replace a relay that sticks or fails its specified release test.
- Correct a low-voltage supply problem if confirmed.
- Repair a confirmed reductant control module fault or apply an applicable update.
Can I keep driving?
A short drive may be possible if the vehicle behaves normally, but get the relay timing fault checked soon because the DEF control system may not follow its intended shutdown sequence. Heed any reductant or starting-restriction warning, as continued faults can lead 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.