Yes. When we bought the car we were informed that there was a fault for glow plug #4 or 5 (can't remember just now) and that the plug had been replaced and the fault remained. So that pretty much points to the module being bad.

Given that the thermostat was also failed open, and the additional duty that the cold running engine puts on the glow plugs has caused failures before, based on my research.

The module is buried under the intake, under the coolant pipe that bolts to the block. If you remove the coolant pipe, I'm sure its much easier. But otherwise it requires snaking things around and the hardest part was unplugging the connectors with no room to work.

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