peter_zimmermann8
A5 TFSI Power Loss + CEL Needs Expert Diagnosis
4 comment(s)
peter_zimmermann8 (Author)
Thanks for sharing your experience. I had almost identical symptoms with my A5 last winter with check engine light and power drops. The fault code pointed to boost issues too and I was worried about expensive turbo repairs. Turned out it was just a faulty boost pressure sensor causing the car computer to get wrong readings. Did your ECU reset and diagnostics fully solve the problem? Would be helpful to know what the repair ended up costing and if youve had any similar dashboard light issues since then.
andreasschwarz1
Having my ECU reset and getting proper diagnostics completely resolved the power issues. The auto scanner confirmed all fault codes were cleared and havent returned in 4 months of driving. The check engine light hasnt appeared since the repair. The total cost came to 180 Euro for removing the problematic third-party tune and running a complete system diagnostic check. While not cheap, it was far better than risking long-term engine damage from improper tuning. The car computer now shows normal boost readings and the engine runs smoother than when it had the aftermarket modifications. The shop confirmed the tune was pushing unsafe boost levels, which triggered the multiple fault codes and power reduction mode. Getting back to factory settings was definitely the right call, the performance is more consistent and I have peace of mind knowing theres no risk to engine components.
peter_zimmermann8 (Author)
After getting recommendations, I took my A5 to a specialist shop for proper vehicle diagnostics. The mechanic hooked up their professional auto scanner and found the boost sensor was sending incorrect signals, triggering the fault code and power reduction. The repair was straightforward, replaced the faulty sensor for 230 Euro including parts and labor. The check engine light cleared immediately and power returned to normal. Total time at the shop was under 2 hours. Really glad I got a second opinion instead of jumping into major repairs. The car runs perfectly now with no warning lights or power issues for the past 2 months. Sometimes the simplest explanation is the right one. Thanks for the input about checking ECU settings too. Will keep that in mind if any similar issues pop up in the future. Having a reliable diagnostic code reading made all the difference in getting to the real problem quickly.
Join the discussion now:
andreasschwarz1
Just went through something similar with my A4 2.0 TFSI. The dashboard light and power loss symptoms matched exactly what happened after a third-party chip tuning. The car computer showed multiple fault codes related to boost pressure and engine management. The root cause was incompatible software mapping from the aftermarket tuning. This required a complete reset of the Engine Control Unit (ECU) to factory settings and professional diagnostics to verify no hardware damage occurred. The issue was serious enough to potentially void the powertrain warranty. Vehicle diagnostics revealed the tune had pushed boost levels beyond safe parameters. The fix involved removing the modified software and performing a thorough system check of turbo components. Main warning signs of faulty tuning: Sudden power loss, Erratic boost behavior, Multiple check engine light triggers, Rough idle, Poor fuel economy Best approach is getting car diagnostic work done at a shop specializing in ECU programming. Generic scan tools often miss the deeper software-related issues that cause these symptoms.