P0418

P0418

Secondary Air Injection Pump Relay Output Stage, Bank 1 - Open Circuit

Diagnostic conditions
- Time after the engine is started longer than 10 seconds
- Battery voltage between 10 V and 16 V

Possible cause of fault
- Fuse F12 faulty
- Power supply to relay faulty
- Open circuit in control line from DME to secondary air injection pump relay bank 1
- Secondary air injection pump relay, bank 1, faulty
- DME control module faulty

Affected terminals
DME control module connector A, pin 46, and secondary air injection pump relay, bank 1, pin 2

Diagnosis/troubleshooting

NOTE:
- If connector A is disconnected from the DME control module and the ignition is or was switched on, the 'DME Control Module TIMEOUT' fault is recorded in many control modules.
- If control module connector A was disconnected from the DME in the course of troubleshooting or if the voltage supply was interrupted elsewhere (battery, fuse), the throttle adjusting unit must be adapted.
- The output stage diagnosis only recognizes an open circuit in the relay control circuit. Open circuits in the load circuit are diagnosed via the oxygen sensor (secondary air injection pump does not work, exhaust too rich) and are assigned a different error code.

Part 1:

Part 2: