VW Fox Diesel Power Loss Due to Faulty MAP Sensor

Had a similar issue with my VW Polo 1.6 TDI from 2011. The symptoms matched exactly, power loss, rough running, and increased fuel consumption. The MAP sensor was indeed faulty, but during diagnostics, the mechanic found a significant vacuum leak in the intake manifold. This was causing incorrect readings from the manifold pressure sensor, making the engine run with wrong air-fuel mixtures. The repair involved: Testing the MAP sensor functionality, Smoke testing the intake system, Replacing cracked vacuum lines, Installing a new MAP sensor, Clearing fault codes It was a serious issue that needed immediate attention because running with incorrect air-fuel mixture can damage other engine components over time. The vacuum leak was making the engine compensate incorrectly, which explained the high fuel consumption. After fixing both the vacuum leak and sensor replacement, engine performance returned to normal. The idle smoothed out, power was restored, and fuel economy improved significantly. These symptoms should never be ignored as they can lead to more expensive repairs if left unchecked. A reputable shop with proper diagnostic equipment is crucial for this type of repair, as proper testing is needed to differentiate between sensor failure and actual vacuum leaks.

Thanks for sharing those details about your Polo repair. My Fox had almost identical symptoms last spring and it turned out to be manifold pressure sensor related too. I got it fixed but wanted to ask, what was your total repair cost? I paid around 350€ including parts and labor, wondering if that was reasonable. Also curious if youve had any other engine performance issues since the sensor replacement and vacuum fix?

After getting the repairs done at my regular shop, I can confirm the total came to 235€, which covered fixing the large vacuum leakage and replacing the faulty manifold pressure sensor. This price seems pretty reasonable compared to what you paid. Since the MAP sensor replacement and vacuum leak repair, the engine has been running perfectly. No more performance issues, rough idling, or excessive fuel consumption. The intake manifold system is working as it should, and the sensor readings are now accurate. The thorough diagnostic process was worth it, they identified both the sensor failure and vacuum leak issues correctly the first time. The repair has proven reliable with no recurring problems over the past months. A properly functioning manifold pressure sensor is crucial for engine performance, and getting both issues fixed together likely prevented additional wear on other components. If youre experiencing similar symptoms again, getting a proper diagnosis with specialized equipment is essential to pinpoint whether its sensor-related or a vacuum issue.

Thanks for the input. After dealing with those frustrating symptoms, I finally took my Fox to a different mechanic last week. Their diagnostic equipment quickly spotted the failing manifold pressure sensor, plus they found a small crack in one of the vacuum lines connected to the intake manifold. The total repair came to 350€, bit more than some others paid but included full diagnostic testing, the new sensor, vacuum line replacement and labor. The car sensors are all working perfectly now and the engine performance is back to normal. No more rough running or excessive fuel consumption. Glad I switched repair shops, the new mechanic was thorough and actually explained what they were checking. Much better experience than my previous attempts to get this fixed. The car runs like new again and I havent had any issues since the repair. Really helped to know what others experienced with similar problems before going in.