wolfgang_loewe9

Siena knock sensor wiring issue

I'm having a problem with my 2005 Fiat Siena, gasoline engine. The check engine light is on, and I've noticed higher fuel consumption and some uneven idling. I scanned the car and it's showing a defective knock sensor. I've checked the sensor itself, and it seems okay, but I suspect the cable or plug connection might be the culprit. Has anyone experienced something similar? Any tips before I start tearing things apart?

A 2005 Fiat Siena owner experienced a check engine light, increased fuel consumption, and uneven idling, with a diagnostic scan indicating a defective knock sensor. Despite the sensor appearing functional, the issue was suspected to be with the wiring or plug connection. After inspecting the wiring, a broken wire inside the connector was discovered and repaired, resolving the problem and restoring normal engine performance.

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4 comment(s)

I had a similar issue with my old Opel Astra a few years back. Check engine light, poor fuel efficiency, the works. While the sensor itself seemed fine, the wiring harness leading to it was corroded. Might be worth inspecting yours closely.

Thanks for the info! When you say corroded, was it obvious, or did you have to do some deeper digging? I gave the plug a quick visual inspection, but didn't see anything glaring.

In my case, it was somewhat hidden under the protective sheathing of the wire. I only noticed it after carefully unwrapping the harness. Given your symptoms and error code, I would strongly advise checking the connection and the wire itself. If you're not comfortable with electrical repairs, I would recommend taking it to a workshop.

Thanks a lot for your advice! It was indeed the wiring - I found a broken wire inside the connector. I had it repaired at a local workshop and the check engine light is now off. The final bill was 95€. Fuel efficiency seems to be back to normal and the engine idles smoothly now.

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FIAT

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SIENA