VW Lupo Power Loss: Engine Sluggish When Accelerating

Having some experience with VW engines, I dealt with a similar issue on my 2005 Polo, which shares many components with the Lupo. The sluggish performance and reduced power symptoms match what I experienced after having a third-party chip tuning installed. The check engine light came on, and using an auto scanner revealed multiple fault codes related to the engine management system. I first tried basic fixes like clearing the fault codes, but the dashboard light kept returning. Finally took it to a workshop where they found the aftermarket tuning was causing conflicts with the original ECU programming. The fix involved removing the modified chip settings and restoring factory settings, which cost 180€ including diagnostic work. Before suggesting specific solutions, could you share: What engine size does your Lupo have? Have you had any performance modifications done? When was the last time you had regular maintenance? Does the reduced power happen all the time or only in certain conditions? This information would help determine if your issue is similar to what I experienced with the faulty tuning or if its something else entirely.

Thanks for sharing your experience. Had my last service done at 124000km and no performance mods installed. To update on my issue, disconnecting the battery for 30 minutes seemed to temporarily fix the sluggish performance, but the problem returned after about 50km of driving. The car diagnostic scan shows code P0122 now. The dashboard light keeps coming back despite clearing it with my vehicle diagnostics tool.

Based on your update and the fault code P0122, your issue seems different from my ECU tuning problem. This specific code points to the throttle position sensor (TPS) circuit, which matches the symptoms youre experiencing. The temporary fix from disconnecting the battery makes sense, as it reset the car computer temporarily. On my Polo, I once had a similar TPS-related fault that caused reduced engine power. The sensor was giving incorrect readings to the car computer, making the engine management system default to a reduced power mode as a safety measure. Few things worth checking: The wiring harness to the TPS might be damaged or loose, The sensor itself could be dirty or failing, The throttle body might need cleaning In my case, a thorough throttle body cleaning didnt solve it. The final fix required replacing the TPS, which cost about 150€ including labor. The scan tool readings returned to normal after that, and the power issues disappeared completely. Since your symptoms persist after the battery reset and the check engine light keeps returning with the same fault code, Id lean towards a faulty sensor rather than just a temporary glitch.

Thank you everyone for the replies. Just wanted to update that you were right about the throttle position sensor. Had it checked at a workshop where they confirmed the diagnostic code P0122 was indeed caused by a faulty TPS. They cleaned the throttle body first but that didnt solve the issue, so ended up replacing the sensor. Total cost was 165€ including vehicle diagnostics and labor. The sluggish performance is completely gone now and no more reduced engine power warnings. The car runs like new again and no fault codes have returned after a week of driving. For anyone finding this thread later with similar symptoms, getting the proper car diagnostic scan done early saved me from trying unusual fixes. The specific fault code really helped point to the exact problem.