Possible causes

– Faulty Engine Control Module (ECM) power relay
– ECM power relay harness is open or shorted
– ECM power relay circuit poor electrical connection
– Faulty (ECM)

Tech notes

Check all the ECM fuses, if the fuses are OK try replacing the ECM relay.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0685 Description

The Engine Control Module (ECM) has detected that the ECM remains powered up after the ignition key has been turned off

P0685 Information for specific makes

P0685 ACURA
P0685 AUDI
P0685 CHRYSLER
P0685 DODGE
P0685 FORD
P0685 HONDA
P0685 HYUNDAI
P0685 ISUZU
P0685 JEEP
P0685 KIA
P0685 MAZDA
P0685 MITSUBISHI
P0685 SUZUKI
P0685 VOLKSWAGEN