theresakoenig49
V70 preheating lamp stays on
Summary of the thread
A 2011 Volvo V70 diesel had issues with the preheating lamp staying on, the check engine light illuminated, and black smoke during acceleration. The suspected causes included a defective preheating control unit or faulty cable connections. It was suggested to check the glow plugs and consider the preheating unit as a potential issue. The problem was confirmed to be a defective cable connection on the preheating control unit, which was resolved at a workshop.
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4 comment(s)
theresakoenig49 (community.author)
Thanks! I haven't checked the glow plugs directly. How would I test them to see if they are shorted? The smoke appears to be black.
annamayer4
Black smoke usually means too much fuel or not enough air. Since it started with the preheating issue, and you haven't messed with the engine's fuel settings, my guess is the preheating unit is indeed the culprit. It's probably sending bad signals to the engine management system. I'd suggest taking it to a workshop to confirm. Faulty cables can be tricky to diagnose properly.
theresakoenig49 (community.author)
Thanks for the insights. I took it to a workshop, and they confirmed it was a defective cable connection on the preheating control unit. The repair cost me 95€. Problem solved!
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VOLVO
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V70
annamayer4
Sounds like a pain! Before you tear everything apart, have you checked the glow plugs themselves? If one's shorted, it could confuse the preheating unit and cause those symptoms. Also, is the smoke black, white, or blueish? That can point to different problems.