Pre-heating device (Audi A4 B8)

The pre-heating system is controlled by the glow plug control unit "J179." The control unit features a self-diagnostic function. If the pre-heating device fails, an error entry is stored in the engine control unit "J623". System check. the pre-heating function is described in "Guided Troubleshooting." To achieve the quick-start function, the electronically controlled glow plugs are connected to a separate glow plug control unit. Each glow plug is controlled and diagnosed separately. After diagnosing the glow plug control unit actuators, wait 60 seconds. The ignition remains on. If you don't wait 60 seconds (the ignition turns off and on again), the glow plug pins can be damaged (due to re-heating). The glow plug pin control is dependent on the coolant temperature.

Glow plugs, Hall sensors, engine speed sensor