VW Lupo Diesel Hard Start Points to Failing Cam Sensor

Had the same symptoms on my 2006 VW Polo TDI last winter. The rough idling and stalling engine were clear signs of a failing camshaft position sensor. The check engine light kept coming on intermittently. The camshaft sensor was actually fine, but the wiring harness connecting to it was damaged. Found corroded pins and a partially broken connector. The wire insulation had worn through, causing intermittent connection issues and false readings. The repair involved replacing the entire sensor wiring harness from the ECU to the sensor. While not a complex job, accessing the connection point required removing several components to reach the back of the engine. A proper diagnosis was crucial since similar symptoms can come from other sensors too. This was a serious issue that could have led to complete engine failure if left unaddressed. When the camshaft position cant be accurately read, the engine timing gets thrown off, leading to poor performance and potential engine damage. The fix restored proper engine performance and resolved both the hard starting and power delivery issues. Definitely worth having a professional shop do a thorough diagnostic before replacing parts.

Thanks for sharing your experience. The symptoms match what I had with my Lupo, those starting issues and timing problems can be really frustrating. After reading about your wiring harness problem, I wonder if that might have been my issue too, since my check engine light was also flickering on and off. My mechanic ended up finding multiple sensor failures, including a crankshaft position sensor that was causing similar symptoms. Did you remember roughly how much the repair cost in your case? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up?

The repair turned out great, just had it done last week. The camshaft sensor issue was exactly what caused those intermittent check engine warnings and poor starting. The mechanic found a loose connection in the sensor wiring that was causing the problems. Total cost was 95€ for fixing the cable connection, which was much better than replacing the entire sensor unit. Since the repair, the engine misfire problems completely disappeared and the car runs perfectly. No more stalling engine or hard starts in the morning. Your mention of the crankshaft position sensor is interesting, these sensors often work together, so when one shows problems, its worth checking both. Good thing your mechanic did a thorough check. From my experience, once the proper connection to the camshaft sensor was restored, all those frustrating symptoms cleared up. The engine power returned to normal and the inconsistent performance issues were resolved.

I finally got my Lupo fixed after dealing with those annoying starting problems. The mechanic did a full diagnostic scan and found the issue was actually a combination of problems. Just like you mentioned, the wiring harness needed attention, but they also discovered a failing camshaft position sensor. The repair took about 3 hours total and cost 280€, including parts and labor. They replaced both the sensor and fixed some damaged wiring. Since the fix, the engine misfire problems have completely disappeared. No more timing issues or rough starts in the morning, and the check engine light hasnt come back on. Really glad I got it properly diagnosed this time instead of just guessing at the problem. The car runs like new now, much better acceleration and smoother overall performance. Thanks for pointing me in the right direction with your experience. Makes a huge difference getting advice from someone whos been through similar issues.