Audi Q8 Timing Chain Issues Causing Power Loss

Had a similar issue with my 2018 Audi Q7 last year. Have some experience working on cars but leave the complex stuff to professionals. The symptoms match exactly what I experienced, sluggish performance, engine misfire symptoms, and the ECU showing timing-related fault codes. Initially thought it was a timing chain issue, but it turned out the crank sensor was failing to provide proper reference values for engine synchronization. The sensor was not giving accurate positioning data to the ECU, causing timing and performance issues. The fix was straightforward, replaced the crankshaft position sensor. Total cost was 340 Euro including parts and labor. Workshop had it done in about 2 hours. Before jumping to conclusions about the timing chain, which would be much more expensive, best to have the sensors checked first. These symptoms often point to sensor issues rather than mechanical problems. What engine variant does your Q8 have? Would help to know the exact engine code to provide more specific insights about common issues with that particular powertrain.

Thanks for the detailed response. Just had my last service at 55000 KM and never had timing issues before. Based on my recent diagnostic scan, getting error code P0016 which seems to confirm the timing correlation issue between crankshaft and camshaft positions. Interesting that your sensor replacement solved similar symptoms. Will definitely have the shop check the sensors first before exploring more extensive timing chain repairs. Running the 3.0L TFSI engine code CWGD. Getting it to the shop next week, hoping for the sensor scenario rather than a full timing chain job.

Thanks for providing that additional info about the P0016 code. With our Q7/Q8 TFSI engines, that specific reference value error between crankshaft and camshaft positions can indeed be tricky to diagnose correctly. After my crankshaft sensor replacement, I had about 15000 KM of trouble-free driving. However, the misfire symptoms eventually returned and the timing chain had actually stretched beyond spec. The initial sensor issue masked the developing timing chain wear. For the timing chain repair, labor time was around 12 hours since they needed to access the front of the engine. Total cost came to 2800 Euro including new chain, guides, and tensioner. While expensive, it resolved all performance issues and restored proper reference values between the crankshaft and camshaft. Given your mileage and that P0016 code, have them check both the sensors and measure timing chain stretch. Sometimes a worn chain can cause similar symptoms even before it completely fails. Better to catch it early if thats the underlying cause.

Thanks for the insights on your Q7 experience. The P0016 code definitely has me concerned, but your repair journey helps put things in perspective. Good point about checking both the sensors and chain stretch. Will have them do a complete diagnosis since attempting the sensor fix first could mask a developing timing chain issue like in your case. Rather catch any chain wear early than risk more engine damage. Having the shop do a thorough check next week. The 2800 Euro timing chain repair cost is steep but still better than replacing a damaged engine. Will update once I know whether its just sensors or if I need the full timing chain service. Fingers crossed its just the crankshaft sensor causing the engine synchronization issues and misfire symptoms.