How to test a MAP sensor OFF CAR

MAP or 'Manifold absolute pressure' sensors are another of the 'family' of electronic sensors used by modern Electronic Fuel Injection systems. The car's computer (ECU) needs to know how much air is entering the engine, together with many other inputs, to calculate fueling and ignition parameters.

Often symptoms like poor starting, excessive fuel consumption, poor emissions and surging can be caused by the ECU receiving an inaccurate signal from the MAP.

Sure, we can use a code reader to see what fault codes (if any) have been recorded but those fault codes only relate to 'circuits' rather than components.

Knowing how to actually bench test this sensor is a far more accurate way of determining if it is working correctly or not. If it is then you can eliminate it from your investigations, if it is faulty then it will need to be replaced, though there may be other faults too so all wires relating to that circuit should also be checked, just in case there may be a short circuit somewhere (insulation has worn through and the wire has grounded) or maybe a break in the circuit too - anything is possible!

In this video I'm checking a MAP sensor from a 1996 Toyota Rav4, its a 3 door version 4wd with a manual gearbox and is fitted with the 3S-FE 2 ltr, 4 cylinder petrol engine. The method of this test does apply to almost all linear voltage type MAP Sensors, however, you will need to source the specification data for your specific Make, model & year of car as the output voltages can vary, especially between manufacturers.

NOTE: This test is NOT suitable for digital output type MAP sensors.

If you have any questions or comments please leave them in the comments section below...

Andy Mechanic!