How To Diagnose a VW Beetle Glow Plug Code
This bulletin applies to the VW Beetle with a 2.0L TDI engine as well as other VW models with the same engine during the 2009-2015 timeframe.
If the vehicle is displaying MIL ON -- Glow Plug Pressure Sensor faults that are stored in the ECM fault memory, it is important to perform diagnosis prior to replacing the glow plug.
Step 1 — first check for loose connections. You can check for any loose connections by performing a push or pull test of the connectors. If on a push test, a click can be felt or on a pull test, the connector comes off very easily, the connection is most likely the cause. Properly seat the connector, clear any DTCs, and test drive the vehicles. Do not replace the glow plug if a loose connection is found and no faults return after a test drive.
If fault returns, go to Step 2 — check the glow plug by performing a swap of the glow plug from the affected cylinder with a glow plug from an adjacent cylinder without a fault. After swapping the glow plug(s), perform a test drive of the vehicle to attempt to duplicate the DTC. If after swapping the glow plug, the DTC follows the glow plug, there is a faulty glow plug. Replace it. If the DTC stays in the samy cylinder after swapping the glow plug, continue to Step 3.
Check the glow plug wiring harness and connectors. While checking the harness, you can monitor MVB 141 or in UDS equipped vehicles monitor the Maximal_Cylinder_Pressure_Cylinder_X values for each cylinder while manipulating the harness and connectors, watching for changes in the readings. If the harness is found to be at fault, replace the harness.