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leoniebeck3

Avventura preheating control unit fault

My 2014 Fiat Avventura diesel has a defective preheating control unit. The preheating lamp does not switch off, and the check engine light is on. There's also smoke when accelerating. I suspect a defective cable or plug connection. Any thoughts?

Summary of the thread

A 2014 Fiat Avventura diesel exhibited a defective preheating control unit, with symptoms including a persistent preheating lamp, a check engine light, and black smoke during acceleration. The initial suspicion was a defective cable or plug connection. After further investigation and a workshop visit, it was confirmed that a defective cable at the preheating control unit was the root cause of the problem.

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4 comment(s)

hans_krueger1

Hmm, persistent glow plug light and smoke, eh? That does sound like a preheating issue alright. But a faulty connection causing all that? Maybe. You've checked the glow plugs themselves, yeah? A dead glow plug can throw things off, even if the controller is trying to do its job. Any codes being thrown? Knowing the actual error code would help narrow it down, because that could be anything from a dodgy sensor to an injector issue. Is the smoke black, blue, or white? That can also tell you a lot.

leoniebeck3 (community.author)

I have not checked the glow plugs themselves, but I will. Can a defective glow plug really cause the check engine light to come on? The smoke is black. Also, what kind of error code should I be expecting?

hans_krueger1

Absolutely, a duff glow plug can trigger the CEL! The ECU monitors the preheating system, and if it sees a glow plug not pulling its weight, it'll flag an error. Black smoke indicates incomplete combustion – could be the preheating messing with the fuel/air mix, or something else entirely, like fuel injectors not atomizing correctly. As for the error code, you're likely to see something along the lines of "Glow Plug Circuit Malfunction" or "Preheating System Fault." A generic OBD2 scanner should pull the code. Based on the smoke and symptoms, best to get it properly diagnosed. Probably a trip to the workshop is unavoidable.

leoniebeck3 (community.author)

Thank you for the detailed information. I went to the workshop as suggested. As suspected, it was a defective cable at the preheating control unit which was causing the issue. Repair cost 95€.

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FIAT

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AVVENTURA