VW Touareg Knock Sensor Troubles: Rough Idle Alert

I experienced something very similar with my 2016 VW Tiguan last summer. Having some experience with car repairs, I first thought it was just a minor check engine light issue, but the symptoms matched yours exactly, rough idle and increased fuel consumption. After the malfunction indicator kept showing up, I had the car diagnosed. The mechanic found that the knock sensor connection was loose, with a damaged wire harness affecting the ignition timing. The sensor itself was fine, but the cable connection needed fixing. The repair involved replacing the wiring harness and properly securing all connections. Total cost was 95€ for parts and labor. Since the fix, fuel consumption returned to normal and the rough running completely disappeared. Before you head to a workshop, could you share: Are there any other warning lights showing? Did you notice any changes in engine performance before the light came on? Have you recently had any other engine work done? This could help determine if your issue is similar to what I encountered. The knock sensor system is crucial for proper engine operation, but sometimes the problem lies in the connections rather than the sensor itself.

Thanks for sharing your experience. Since my last service at 11000km, I have noticed a gradual decline in performance. No other warning lights are showing on the dashboard, and I have not had any recent engine work done. The rough idle and engine knock started suddenly during normal driving conditions. The malfunction indicator light appeared shortly after I noticed these symptoms. Some auto repair forums suggest checking the wiring connections first, as you mentioned, which seems like a sensible starting point before replacing the entire knock sensor assembly. I will get it checked at a workshop to diagnose if its a similar wiring issue to what you experienced with your vehicle. The warning light and increased fuel consumption are concerning enough to warrant professional inspection.

Thanks for the additional details. Your symptoms do sound nearly identical to what I experienced with my Tiguan. The gradual performance decline before the sudden onset of problems particularly matches my case. Since you mentioned no other warning lights and no recent engine work, this strengthens my suspicion about the wiring connection. In my case, the gradual performance loss was due to the harness deteriorating over time, affecting the knock sensor signals and ignition timing accuracy. The workshop should definitely start by checking the wiring harness and connections around the knock sensor. When they diagnosed my vehicle, they found the connections had worked loose over time, causing intermittent signal issues. This explained why the malfunction indicator would sometimes reset temporarily if the wire shifted back into position. One thing I learned from my experience, while the fuel efficiency drop is concerning, addressing this promptly actually prevented more serious engine issues. The knock sensor plays a crucial role in preventing engine knock by adjusting ignition timing, so any problems with its operation need quick attention. Would you mind updating the forum once you get the diagnosis? It would be helpful to know if your Touareg has the same underlying issue as my Tiguan did.

Thanks for the detailed follow-up. These insights about the wiring harness and gradual deterioration make a lot of sense given my car problems. Your experience with poor performance and engine knock symptoms matches what I am seeing. I have scheduled a workshop appointment for tomorrow morning. I specifically asked them to inspect the wiring harness and connections around the knock sensor first, before jumping to replacing parts. The mechanic seemed to agree this was a logical starting point given the symptoms. The connection between fuel efficiency, ignition timing, and the knock sensor system is clearer now. I am relieved to hear that fixing the wiring resolved your issues without needing major repairs. My rough idle and performance issues do seem very similar to what you described. I will definitely post an update once I get the diagnosis and repair completed. If it turns out to be a wiring harness issue like yours, this information could help other owners experiencing similar problems. Thanks again for sharing your repair experience, it has helped narrow down the likely cause.