P0688 AUDI – Electronic Control Module Power Relay Control Circuit Open

P0688 AUDI Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P0688 AUDI Possible Causes

Weak battery,Low voltage while cranking,Faulty Engine Control Module (ECM) relay,Blown ECM fuse,Faulty ECM,ECM harness is open or shorted,ECM circuit poor electrical connection

P0688 AUDI Description

The Engine Control Module (ECM) monitors the power inputs. The ECM sets the OBDII code when the ECM remains powered up after the ignition switch has been turned OFF.