Manifold Sensor Symptoms? Check These Common Signs

Had a similar issue with my 2006 Chevy Aveo last year, I've got moderate experience with basic car maintenance. The symptoms matched yours exactly, poor acceleration, high fuel consumption, and that annoying check engine light. Initially thought it was just the MAP sensor failing, but my mechanic found a significant vacuum leak at the intake manifold. The manifold sensor was giving false readings because of the leak. Total fix was around 235 for parts and labor, they replaced a cracked vacuum line and recalibrated the manifold sensor. Quick question, have you noticed any unusual whistling sounds from the engine bay? Also, what engine size does your Nubira have? This info would help narrow down the potential trouble spots. Before heading to the shop, try checking for obvious vacuum leaks around the intake manifold, you might hear a hissing sound with the engine running. Could save you some diagnostic time.

Thanks for your insight on the vacuum leak possibility. Last service was 2 months ago and I'm at 96549 KM now. After reading your response, I actually did a quick check and noticed a faint whistling near the intake manifold when revving. It's a 1.6L engine, by the way. The manifold pressure sensor readings are all over the place when I checked with a basic OBD scanner. Getting error code P0106 which seems to confirm the MAP sensor issue, but your vacuum leak theory makes a lot of sense given the whistling. Will probably have both the sensor and vacuum lines checked thoroughly since they seem related. Good call on checking for hissing sounds, definitely hearing something that shouldn't be there.

Thanks for the update and those mileage details. After dealing with my Aveo's similar issues, hearing about that whistling sound and the P0106 code really confirms my initial thoughts. Just like your case, my manifold sensor readings were erratic, but the root cause wasn't just sensor failure. What's interesting is that my repair actually uncovered multiple small vacuum leaks that developed around the same mileage point (around 95,000 km). The pressure sensor was giving false readings because it couldn't maintain proper vacuum readings with those leaks present. Smart move using the OBD scanner, that P0106 code is pretty telling. My case ended up needing both a sensor replacement and vacuum line repair because the faulty readings had stressed the original sensor. The intake manifold setup on these engines is pretty similar, and they tend to develop these issues around the same mileage points. Definitely get both checked, the sensor replacement alone might not solve it if there's an underlying vacuum issue. The total repair cost might be a bit more than just a sensor, but fixing both will prevent the new sensor from getting damaged by the same problem.

Thanks everyone for the help. After visiting my mechanic today, turns out both issues needed attention. The manifold pressure sensor had indeed failed, but they also found two small vacuum leaks that were messing with the engine performance. Total repair came to 310, more than just a sensor replacement would have cost, but at least it's properly fixed now. The engine performance is back to normal, fuel consumption has improved, and that annoying check engine light is finally off. Really glad I checked for those vacuum leaks before going in, saved some diagnostic time and helped the mechanic zero in on the problems faster. Definitely learned something here about how car sensors and vacuum systems work together. When the manifold sensor starts acting up, it's worth checking the whole intake system. My car's running like new again, definitely worth fixing both issues at once rather than dealing with repeated problems.