7 signs of a broken MAP sensor you look out for and how to deal with it


To avoid having ECM malfunctioning and ultimately problem with the whole engine, it is highly recommended you pay attention to the MAP sensor.

The engine control module measures and calculates the flow of air in the newer engine through either a mass air flow (MAF) or manifold absolute pressure (MAP) sensor. Both can be used by turbo-charged engines but one of the two is often used by naturally-aspirated engine. When there is a failing or broken MAP sensor, there would be severe malfunction in the ECM and subsequently the entire engine. This is why it is very important to maintain and repair the MAP sensor when needed, to keep the engine running smoothly and effectively.

MAP sensor- How it works

The MAP sensor data is made use by the ECM in running vital calculations such as fuel injection pulse, engine load and spark advance. When it is resting, atmospheric pressure at the level of the sea is being read by the MAP sensor. Due to the fact that pressure of the atmosphere varies with altitude and weather, the “zero” point calculation is being carried out by the ECM just before the start of an engine, fine-tuning spark and injection of fuel mapping from that point.

WTF is a MAP Sensor

During the idle time, pressure intake is often from 16-22 in.Hg. This is due to it being lower than atmospheric pressure, hereby, the intake is faced with air rush. When the throttle is wide open, there is always a nearly equal intake and atmospheric pressure.

Broken sensor signs to look out for

This might look complicated but we assure you that taking note of these signs is quite simple. When there is a scenario of failure with the MAP sensor just because of being contaminated, damaged or clogged, it means there is a big issue you have to respond to quickly. However, it is also possible that the heat in the engine overcooks the Map sensor electronics or crack vacuum lines. When it goes bad, it will be difficult for the engine load calculation to be precisely done by the ECM, meaning the ratio of air-fuel will be confronted with more or less fuel. Like earlier mentioned, seeing those signs is pretty easy and here is what you should look out for when there is broken sensor on  NaijaCarNews.com.


Where is usually influence of MAP sensor on the data processed by ECM, which affects engine performance

Poor fuel economy

When there is low reading or no vacuum by the ECM, it draws up an assumption that there is high load on the engine, hereby dumping in more fuel and advances timed spark. This could result to fuel consumption in excess, poor fuel efficiency and a possible detonation.

Absence of power

When high vacuum is being read by the ECM, providing an assumption that the load on the engine is low, hereby cutting the fuel injection and retard the timing of the spark. Alternatively, it seems like a good thing since the consumption of fuel will reduce. But by implication, the car engine will lack the necessary power for passing and acceleration.

Failed emission inspection

Where there is no correspondence between the load and the fuel injection, a MAP sensor when broken would lead to an increase in harmful emissions. Too much fuel will generate higher carbon monoxide (CO) and hydrocarbon (HC) emissions while low fuel would lead to emission of higher nitrogen oxide.

Rough idle

Your car engine will be starved if there is not enough fuel injection, which could lead to rough idling and probably random misfiring by the cylinder.

Hard starting

It is usually hard to start the engine when there is too much rich or lean mix. If when you put foot on the accelerator is the only time you can start your engine, which implies a possible MAP sensor problem.

Stalling or Hesitation

Stepping on the gas might not really give you any joy when you start from a stop or attempt to pass a maneuver. This often happens when the ECM is giving to you a lean mixture based on Map sensor readings that is faulty.


If you do not act swiftly, you will incur more problems on yourself financially, and the car

Check Engine light

When you take the age of your car into consideration, diagnostic trouble codes (DTC) for MAP sensor may vary from simple sensor or circuit faults to range or correlation fault. Nothing would definitely be read by a dead MAP sensor while unuseful data will be supplied to the ECM by a failing MAP sensor. These would include low engine vacuum when the crankshaft position sensor (CKP) and the throttle position sensor (TPS) indicate the engine at idle.


A dead MAP sensor gives no correct diagnosis

How to solve MAP sensor problems

Just like we all know that a working MAP sensor is an integral part of the vehicle maintenance. After you have checked the following element, it is overly rational in knowing whether it is just simple fixes or you might need a replacement.


You need to do this by starting to check the wiring and the connector. This connector should be firmly connected and there should be clean and straight pins. When there is corrosion or case of bent pins, the MAP sensor might be confronted with problem. At the same time, the ECM and MAP sensor connecting wires should be intact. Short circuit could also be caused by chaffing, and breaks would result to open circuits.

How to Test a MAF or MAP Sensor With a Multimeter - Plus an Operations Guide


The intake manifold is connected to some MAP sensor by a hose. Check if the connection of the MAP sensor to the hose is intact. Make sure you check if the port is free of debris or carbon deposits. This dirt could block the hose and eventually result to poor reading by the MAP sensor.


If there is proper connection of the sensor, both electrically and to the intake manifold, make use of scan tool or voltage meter with vacuum gun to carry out an inspection on the output of the MAP sensor. You will need to measure the voltage against full vacuum or no vacuum by looking up the chart. If the chart doesn’t sync with the output of the MAP sensor, you should replace the sensor.


You might need to contact an expert if you find the repair way too technical for you to handle

Final words

Remember to always pay attention to these signs earlier enough to reduce the cost of repair. When you sense a failing MAP sensor, take your car to an expert to fix it for you.

>>> Check out more about car maintenanceroad usage and safe driving right here on Naijacarnews.com!

Oluwaseun Adeniji