Vehicles with a bad manifold absolute pressure (MAP) sensor typically run rough while accelerating, decelerating or idling. Other common symptoms include increased fuel consumption and sudden jerks or hesitation while accelerating. Drivers may detect a strong smell of gas after the engine has warmed up.
A MAP sensor works together with the electronic control unit, or ECU, in cars that are equipped with fuel injection systems. The MAP sensor helps the ECU calculate the amount of fuel needed for efficient consumption by monitoring the engine's mass airflow rate. MAP sensors are not critical components however, and cars with bad MAP sensors will still run, albeit with less efficiency and greater fuel consumption. Ignoring a faulty MAP sensor can lead to other engine problems, so it still should be checked if a problem is suspected.
To check for a faulty MAP sensor, a complete engine diagnostic will need to be performed. Replacing a MAP sensor requires some technical skill. However, not all faults will call for a sensor replacement. Sometimes, symptoms linked with a MAP sensor may be caused by something less severe, such as a hole in the hose attached to the intake manifold. Having a car inspected by a professional is the surest way of diagnosing the problem and preventing the fault from worsening.