VW Eos Sluggish: Crankshaft Sensor vs Timing Chain Issues

As someone with moderate car repair experience, I had a very similar issue with my 2008 VW Golf GTI. The engine light came on repeatedly, showing crankshaft position sensor-related trouble codes. The symptoms matched yours exactly, sluggish acceleration and poor fuel economy. After some initial troubleshooting, the workshop discovered a faulty crankshaft sensor. The reference value readings were completely off, causing the engine management system to run inefficiently. They replaced the sensor and recalibrated the system, which resolved all the symptoms. Total cost was 340€ including parts and labor. However, these symptoms could have multiple causes. To provide more specific guidance, could you share: The exact engine code of your Eos, Any trouble codes from your diagnostic scan, Whether you notice the issues more during cold starts, If there are any unusual sounds from the timing chain area In some cases, what appears as a cam sensor or crankshaft sensor issue could actually be related to timing chain wear. Getting this detailed information would help determine if your situation matches what I experienced or might be something different. The repair was straightforward in my case, but proper diagnosis is crucial since similar symptoms can have different root causes.

Last service was at 92000km. The timing chain noise is definitely more noticeable now. After reading your input, I checked the timing chain area more carefully and noticed a rattling sound, especially during cold starts. The diagnostic codes are P0016 and P0017, which point to issues with crankshaft and camshaft positions. The engine code is BUB, and considering the mileage, timing chain wear seems increasingly likely. The reference value readings are way off from normal specs. Do these details help narrow down whether its more likely to be a sensor issue or timing chain problem? Some mechanics suggested replacing just the cam sensor first since its cheaper, but Im concerned about potential engine damage if its actually the timing chain.

Thanks for providing those details, your symptoms strongly point to timing chain issues rather than just a sensor problem. The combination of P0016/P0017 codes with noticeable chain noise during cold starts is a classic indicator of timing chain wear in these engines. When my GTI showed similar symptoms around 95000km, I initially hoped it was just the cam sensor too. However, after checking the timing chain stretch with diagnostic equipment, it was clearly beyond specs. The misfire and poor performance got worse quickly. I decided to do the complete timing chain service rather than just replacing sensors. The full job included: New timing chain kit, Updated tensioner, Cam sensor replacement, New guides and seals Total cost was 1200€ but prevented potential catastrophic engine damage. The engine light issues disappeared completely and performance returned to normal. Given your BUB engine has similar chain tensioner design to mine, I would strongly recommend addressing the timing chain rather than just sensors. These engines are known for premature chain wear causing camshaft timing issues. Better to fix it properly now than risk major engine damage. The improved fuel economy and restored performance after the repair made it worth the investment. Plus the peace of mind knowing the engine timing was properly sorted.

Thanks for the detailed advice, you've convinced me to go with the full timing chain replacement rather than risk it with just a sensor swap. The symptoms you described with your GTI match mine exactly, especially that chain noise during cold starts. Those BUB engines definitely seem prone to timing chain issues. I've scheduled the work for next week, going for the complete service with new timing chain, tensioner, guides and seals. The 1200€ estimate I got matches what you paid, which helps confirm I'm not being overcharged. While it's not cheap, it's definitely better than risking catastrophic engine damage from a failed timing chain. Really appreciate you sharing your repair experience. The fact that it completely resolved your engine light and performance issues is reassuring. I'll update once the work is done, but I'm feeling much more confident now about getting this sorted properly rather than taking the cheaper sensor-only route.