What happens if the intake pressure sensor is unplugged?
2 Answers
Unplugging the intake pressure sensor will cause engine malfunction and heavier exhaust emissions. The intake pressure sensor, abbreviated as MAP, is connected to the intake manifold via a vacuum tube. It senses the vacuum changes in the intake manifold under different engine speeds and loads, then converts the changes in internal resistance into voltage signals for the ECU to adjust fuel injection volume and ignition timing. The intake pressure sensor uses indirect detection to measure intake air volume and comes in various forms. Based on the principle of signal generation, it can be classified into piezoelectric, semiconductor piezoresistive, capacitive, differential transformer, and surface acoustic wave types.
I've been driving for over twenty years, and unplugging the intake pressure sensor is no small matter. It measures the air pressure in the engine's intake manifold, telling the computer how much air the engine is drawing in for precise fuel injection and ignition. Once unplugged, the computer switches to a fail-safe mode, estimating air volume using preset values, but the margin of error is significant. The result is a sluggish car that accelerates as if climbing a hill and may even stall suddenly, especially dangerous on highways. Fuel consumption typically increases by 15%-20%, and emissions exceed standards, polluting the environment. I once tried unplugging it—the tachometer wavered, the check engine light came on, and the car shook nonstop. Doing this long-term can easily clog the catalytic converter and accelerate piston ring wear. If you find an issue with the sensor, don't unplug it yourself. Check if the connector is dirty or the wiring is loose. If cleaning doesn't work, replace it promptly to save big on repairs.
