XC70 Preheating Lamp and Smoke

Hi, I'm having trouble with my 2005 Volvo XC70, diesel engine. It's got about 140k kilometers on the clock. Recently, the preheating lamp doesn't switch off, and the check engine light has illuminated. I've also noticed some smoke when accelerating, particularly noticeable when the engine is under load. I suspect that the glow control unit might be defective. I checked the wiring and plug connections, and while I didn't find anything glaringly obvious, it all seems a bit suspect. Any thoughts before I take it in? Maybe it's a bad connection somewhere?

4 comment(s)

I had similar symptoms with my XC70. The preheating light staying on, plus the engine light, points to a problem with the glow plug system. Have you run a diagnostic test to pull the error codes? That's the first step. Could be as simple as a faulty glow plug, but if you suspect the control unit, you're probably on the right track.

Thanks for the quick reply! I haven't run a diagnostic test myself yet, I don't have the equipment. I was hoping to avoid a trip to the shop if it was something simple. When you had the same symptoms, was it also a problem with the control unit, or was it something else in the system? Was the 'diesel particulate filter' affected by this? The car needs to pass inspection soon.

Yes, it turned out to be the glow control unit itself. I tried cleaning the contacts but no luck. Given the symptoms, especially the smoke, and the fact you've checked the connections, I'd say get it checked out at a workshop. Prolonged issues with the glow plugs can lead to other problems down the line.

Thanks a lot for the confirmation! I appreciate you sharing your experience. I'll book it in for a proper diagnostic and replacement of the glow control unit. Seems like the 95€ are well invested. Hopefully, that will sort everything out.

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