Manifold Absolute Pressure (MAP) Sensor
WHAT IS A MAP SENSOR ?
In modern vehicles, a computer and a series of sensors control the engine’s fuel consumption and other operations. While you may never have to work on any of these sensors yourself, one in particular is essential to a smoothly running engine — the MAP (manifold absolute pressure) sensor. What is a MAP sensor, and what does it do? When your engine is running funny, it could indicate a failure of this sensor, so here’s a look at what exactly it is that the MAP sensor does.
MAP sensors, or Manifold Absolute Pressure sensors, have two specific responsibilities in the engine management system: measure barometric pressure at key on, and report engine load to the powertrain control module. The powertrain control module uses the information for proper air/fuel mixture control under all operating loads and altitude conditions.
In fuel-injected automotive engines, a manifold absolute pressure (MAP) sensor is used to continuously monitor the amount of air flowing into the engine, so the computer can calculate air density, adjust the amount of fuel to spray into the combustion chamber and adjust the ignition timing. In some vehicles, a mass air flow (MAF) sensor is used. While the two are interchangeable, a MAF sensor measures flow rather than density.
MAP Issues
A failed MAP sensor can cause your vehicle to have a few performance problems. If the sensor is in error, reading too high, it can cause the fuel management system to use more fuel than is needed and decrease fuel economy. Conversely, if the MAP sensor reads too low, the onboard computer will trim back the amount of fuel it thinks is needed and starve the engine, causing it to run erratically and decrease power. In either case, if the sensor isn’t reading properly, it will cause your vehicle to fail emissions testing. Plugging in a diagnostic code reader you may find trouble codes P0068, P0069, P1106, or P1107.
Reasons for a MAP sensor failure can be caused by a few factors. The sensor itself relies on both electronic and mechanical components to function. A vacuum chamber inside the sensor is what allows the the sensor to read changes in the manifold pressure. Over time a leak can develop in the vacuum chamber, making the sensor unable to read correctly. Due to the location of the sensor in the harsh engine compartment environment, years of extreme temperature fluctuations and vibration can also wreak havoc on the internal circuitry. Another failure point can be dirt or other contamination physically preventing the sensor from accessing the intake manifold air flow.
Repair
Difficulty in replacing a bad MAP sensor varies by vehicle. Typically, it’s mounted to the outside of the intake manifold or throttle body using a set of bolts or screws. Unplug the sensor wire and then undo the screws and carefully remove the bad sensor. To install your new one, simply reinstall the screws, plug the wire back in and you’re ready to go. Depending on the vehicle and if a trouble code was set, a diagnostic tool may be required to reset the check engine light.
Many people hear that they have a bad sensor and wonder: What is a MAP sensor? While its job may be a simple one, it’s essential to getting good fuel economy and performance out of your vehicle’s engine for years. If you suspect a MAP sensor failure, your local NAPA AutoCare center has the expertise to handle the problem and get you back on the road.
Check out all the relays, sensors and switches available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on MAP sensors, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.
