VW Lupo Power Loss Points to Faulty MAP Sensor

Had the exact same symptoms on my 2004 VW Polo TDI last month. The drop in power combined with higher fuel consumption strongly indicated a MAP sensor failure, but the real culprit turned out to be a major vacuum leak in the intake manifold. After proper diagnostics, we found cracks near the intake manifold gasket causing false readings from the pressure sensor. The vacuum leak was allowing unmetered air into the system, throwing off the air-fuel ratio calculations. This explained both the power loss and increased fuel consumption. The repair involved replacing the intake manifold gasket and testing all connected vacuum lines. This was a serious issue that needed immediate attention since continuous running with a vacuum leak can damage other engine components. To confirm if its really the sensor, a mechanic can test the MAP sensor output with a diagnostic tool while the engine is running at different RPMs. But given the symptoms, recommend checking the entire intake system for leaks first. Listen for any hissing sounds around the intake manifold area when the engine is running.

Thanks for sharing your experience. Its good to know about the vacuum leak possibility, I will get that checked too. Would you remember how much you ended up paying for the full repair? My VW Lupo has been parked for a few days since the manifold pressure sensor started acting up. I am wondering if fixing the car sensor issues will completely solve my power loss problem or if you noticed any other issues popping up afterwards? Its always helpful to know what to expect with these automotive sensor problems.

Took my Polo to the mechanic last week and got everything sorted. The manifold pressure sensor readings were indeed wrong because of a large vacuum leakage in the intake system. After replacing the damaged parts and fixing the leak, the total bill came to 235€, which included labor and parts. Since the repair, the car runs perfectly again, no more power loss issues. The pressure sensor now gets accurate readings, and fuel consumption is back to normal. Having a proper diagnosis was key, as car sensors can sometimes show symptoms of failure when the real problem lies elsewhere in the intake manifold system. No additional problems have emerged since the fix. The key was addressing both the leak and ensuring the sensor replacement was done properly. A qualified technician should always verify the entire intake system during manifold sensor diagnostics to catch any related issues that could cause similar symptoms down the road. If your Lupo has similar symptoms, getting it checked soon is important since continuing to drive with intake manifold problems can lead to more extensive damage.

Thanks everyone for the advice! Just wanted to update on how things turned out with my Lupo. Finally took it to a local diesel specialist after reading the responses here. Turns out you were right about checking the whole intake system. The mechanic found both a faulty manifold pressure sensor and a small vacuum leak. The engine performance improved dramatically after replacing the sensor and fixing the leak. Total cost was 290€, which included parts and labor. Bit more than expected but worth every cent since the car runs like new again. The fuel consumption is back to normal and the sluggish feeling is completely gone. What really helped was going to a shop that specialized in diesel engines. They spotted both issues right away using proper diagnostic equipment to test the automotive sensor readings. Much better experience than my previous mechanic who just wanted to replace parts without proper testing. Just glad to have the car back running properly. No other engine performance issues have shown up since the repair three weeks ago. Main lesson learned: when dealing with sensor failure symptoms, always get a thorough diagnostic check of the entire system rather than assuming its just one component.