BMW 335d glow plug controller failure causing check engine light, recommended replacement of all six glow plugs on BMW 335d

Some BMW 335d owners report experiencing issues related to glow plug controller failures that trigger the check engine light. These owners often find it necessary to replace both the glow plug control unit and all six glow plugs when faults are detected. The glow plug controller is frequently identified as a common issue, and its replacement is typically recommended alongside the glow plugs. Additionally, some sources indicate that a failed coolant thermostat, particularly in winter, could be a root cause of these problems. Owners are advised to watch for signs of faulty glow plugs, such as the engine warning light illuminating on the dashboard. When diagnosing the glow plug controller, it is important to inspect for broken wires that supply power, as these can indicate underlying issues. Conducting a resistance check on the glow plugs can also be helpful, with an ideal reading around 1 ohm; deviations from this value may suggest a faulty glow plug. Following these recommendations can help owners effectively address glow plug controller failures and maintain their vehicle's performance.