VW Transporter Rough Idle Points to Mount Issues

I had a similar issue with my 2006 VW Caddy. As someone with some hands-on experience working on VWs, those symptoms sound very familiar. The vibration issues started exactly the same way, rough idling and noticeable shaking when stationary. Initially thought it was a rubber mount issue, but after taking it to the workshop, they diagnosed a loose connection in the engine wiring harness. The vibrations were actually caused by misfiring due to a faulty sensor connection, not mount failure. The total repair cost was 95€, which included diagnostic time and fixing the connection. The symptoms you describe could be related to various issues, from defective engine mounts to electrical problems. Before assuming its a transmission mount or engine mount problem, having the electrical system checked would be worthwhile. To better assist, could you provide: Current mileage, Whether vibrations change with engine temperature, If the check engine light shows steady or blinking, Any specific error codes if scanned, When the symptoms first appeared This information would help determine if your issue matches what I experienced or points to something different.

Last service was at 137484km, and since then the vibration has gotten noticeably worse. The vibrations definitely worsen when the engine is cold and tend to smooth out slightly after warming up. The check engine light stays steady rather than blinking. I noticed the issue start about 2 weeks ago, and it has gradually become more pronounced. Had it scanned at a local parts store and got error code P0303, suggesting cylinder 3 misfire. Still, the excessive movement makes me suspect a failed mount could be contributing to the problem. When checking under the hood, the engine seems to move more than normal when giving it gas. The fact that your issue turned out to be electrical rather than a mount failure is interesting. Will definitely have them check the wiring harness when it goes in. Though with the age and mileage of my Transporter, mount wear is still a real possibility worth investigating.

Thanks for the detailed follow-up. The P0303 code on your Transporter matches what I initially saw on my Caddy, but my case had an additional twist. After fixing the wiring issue, the vibrations partially remained, and a deeper inspection revealed that both problems existed simultaneously, the electrical issue and a deteriorated mounting bracket. The engine movement you mentioned while revving is a classic sign of mount wear. In my case, the front motor mount had completely separated from its mounting bracket due to age and stress. The repair shop found rubber pieces had disintegrated, causing excessive engine movement. The total repair ended up being: Wiring harness repair: 95€, Motor mount replacement: 180€, Labor: 145€ The combination of the error code and visible engine movement strongly suggests checking both systems. The cold-start symptoms are particularly telling, failing mounts often show worse symptoms before reaching operating temperature as the rubber becomes more flexible when warm. Would recommend having both the cylinder misfire and mount wear checked during the same visit since symptoms overlap. This approach saved me from making two separate trips to the workshop.

Thanks for sharing your repair experience. Given the combination of the P0303 code and the visible engine movement, I'm more convinced than ever that getting both issues checked makes sense. Your repair costs actually seem reasonable, I was worried it might be much higher. The fact that your mounts had deteriorated to the point of separation is concerning, since my Transporter likely has similar age-related wear on its rubber mount components. The transmission mount is probably due for inspection too, given the mileage. The wiring harness issue you mentioned is definitely worth investigating, especially since fixing it resolved part of your vibration issues. I will make sure to mention this to the workshop when I bring it in. Having them check both the electrical and mounting systems during the same visit should save time and possibly prevent return trips. Appreciate the detailed breakdown of your repair costs, helps set realistic expectations. Will schedule an appointment to have everything inspected and hopefully resolve both the misfire and mounting bracket problems. The cold-start behavior matches what you described, which makes me more confident we are dealing with similar issues.