Glow Plug System, Checking

WARNING: This page is about a different car, the 2016 Audi A6 Quattro. However, it is still accessible from the selected car via links, so may be relevant.

The pre-glow system is controlled by the Automatic Glow Time Control Module -J179-. The control module has On Board Diagnostic (OBD) capable systems.
If there is a malfunction in the preglow system, a fault will be stored in the Engine Control Module -J623- Diagnostic Trouble Code (DTC) memory.
Checking the preglow system is explained in "Guided Fault Finding".
Electronically controlled glow plugs with a separate glow plug control module were installed in order to reach a quick starting function.
Each glow plug is controlled and diagnosed individually.

NOTE:

Wait 60 seconds after each glow plug control module output diagnostic test. The ignition must remain switched on.

If the 60 second waiting period is not observed, (if the ignition switched off and then back on again), the glow plugs could be damaged (by a repeated preglow).

The glow plug control depends on the coolant temperature.