ottodrache1
S80 diesel preheating lamp issue
Summary of the thread
A 2007 Volvo S80 diesel had issues with the preheating lamp staying on, the check engine light activating, and emitting smoke when accelerating. The suspected cause was a faulty preheating control unit, possibly due to a defective cable or plug. Error codes confirmed the issue with the preheating control unit, which can lead to unburnt fuel and smoke. Replacing the control unit resolved the problem, restoring the vehicle's performance.
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4 comment(s)
ottodrache1 (community.author)
Yeah, I had a peek at the error codes, and it's definitely flagging the preheating control unit. But could a faulty unit really cause all those symptoms – the light, the engine light AND the smoke? Or is it more likely a cascading failure of some sort?
manuelschulze2
A defective control unit can definitely trigger all those symptoms. The smoke likely indicates unburnt fuel due to incorrect preheating. If the error codes pinpoint the unit, it's highly probable that's the culprit. Getting it checked by a workshop is the most sensible thing to do.
ottodrache1 (community.author)
Thanks a bunch for the advice! It turned out to be exactly what you said: the preheating control unit. Replaced it, and she's purring like a kitten again. Cost me about 95€ for the part and labour. Cheers!
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VOLVO
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S80
manuelschulze2
Sounds like an electrical fault. Is it possible to read out the error codes? It might point directly to the preheating control unit or a related component in the ignition system.