What it means
The DPF/SCR forced-regeneration request switch — used on commercial vehicles to let the operator force a parked regeneration when the automatic regen has been postponed too often — is open. The ECM cannot honour an operator request for forced regen.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The regeneration control switch lets an operator request a parked regeneration of the diesel particulate filter. The controller monitors the switch circuit and sets this code when it detects an open, so it may not register an operator’s request.
Common causes
Most likely first.
- Open switch wire
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Forced regeneration may not start when requested
How to diagnose it
- Use a scan tool to check for related aftertreatment codes and view the regeneration request input while operating the switch.
- Confirm the switch is being used under the vehicle’s specified conditions for a parked regeneration and note whether the request is recognized.
- Inspect the regeneration control switch, connector, and harness for loose plugs, broken wires, corrosion, or terminals pushed back into the connector.
- Using the wiring diagram and manufacturer’s procedure, test continuity through the switch circuit and check whether the switch closes the circuit when pressed.
- If the switch and wiring pass, test the controller input and connector for an open connection before considering module repair.
Common fixes
- Reconnect a loose regeneration switch connector or reseat a pushed-back terminal.
- Repair a broken wire in the regeneration control switch circuit.
- Replace a faulty regeneration control switch after confirming the harness is intact.
- Repair an open controller connector or circuit if testing locates the fault there.
Can I keep driving?
A parked regeneration may not start on request, so follow the vehicle’s aftertreatment warnings and operating instructions. Continued driving with an unaddressed soot-loading warning can lead to restricted power or a need for service.
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.