MAP Sensor

• A MAP sensor is a small, plastic device (usually colored black) that measures the amount of positive air pressure entering the intake manifold.
• The MAP sensor sends the data to the car’s engine control unit (ECU), which in turn calibrates the fuel injectors to match the amount of air in the cylinders.
• MAP sensors are identified according to the peak pressure they can read: 1 bar MAP sensors are for naturally aspirated engines while 2 bar and 3 bar MAP sensors are used in engines with forced induction systems.
• Keep in mind that using the wrong MAP sensor would affect your vehicle’s performance as the ECU wouldn’t be able to control the amount of fuel to spray into the chambers.
• All MAP sensor identifications share a common pinout style, though the arrangement may vary. There are three pins for ground, sensor output or signal, and constant voltage, which is +5 V.
• Poor fuel economy, failed emission inspection, decrease in power, rough idling, stalling, starting difficulty, and an illuminated malfunction indicator lamp (MIL) are common symptoms of a failing MAP sensor.
• OE MAP sensor replacements on CarParts.com typically cost anywhere between $2 and $280.

Your car simultaneously performs a lot of tasks under the hood for it to run according to how you want it to. The engine, for example, has 40 or more moving components inside it that work altogether as soon as you twist the key in the ignition. Outside of your engine, there are sensors that keep the air, fuel, throttle position, or pressure in check. One of these sensors is called the Manifold Absolute Pressure (MAP) sensor. Here are the important things you need to know about MAP sensors.

This device measures the amount of positive air pressure entering the intake manifold. It is a small, plastic device (usually black) near or directly attached to the intake manifold. Some setups have the MAP sensor mounted after the throttle body or inside the intake manifold. Be careful not to confuse the MAP sensor with the Mass Airflow (MAF) sensor as the MAF sensor determines the flow rate of air entering the engine. 

A MAP sensor constantly monitors the amount of air pressure being sucked into the intake manifold and sends the data to your car’s engine control unit (ECU). Your ECU’s control of the fuel injectors relies heavily on your MAP senor’s reading, as it helps determine the amount of calibrated fuel needed to achieve the ideal combustion.

Before continuing into more detail, here are some important terms and measurements you need to be familiar with. When looking for a MAP sensor replacement, you’ll come across the term “bar”, which is actually a measurement of pressure, just like how one uses PSI for pressure ratings for inflatables.

However, these two measurements differ in relation to applications. PSI, which stands for pound-force per square inch, measures pressure in one-pound force applied on a square inch of an area. Bar, on the other hand, measures pressure as if you’re applying force perpendicularly on a surface.

There are different systems used in measuring pressure, but bar and PSI are the two units more commonly used when talking about MAP sensors. 1 bar is equivalent to 14.5038 PSI. These two are important as MAP sensors are identified based on its capacity to read absolute pressure.

There are three types of MAP sensors depending on your engine’s setup. These are the 1 bar, 2 bar, and 3 bar MAP sensors. Each has its own peak pressure reading capacity. They apply from naturally aspirated engines to forced inducted engines.

1 bar MAP sensor

This sensor is used on naturally aspirated engines. It can read up to 14.7 PSI, which is the atmospheric pressure present as long as you’re inside Earth’s atmosphere. This is rounded off to 1 bar since 14.7 PSI is equivalent to 1.013 bar—hence, its identification. 1 bar MAP sensors are standard on vehicles with naturally aspirated engines. If you’re planning on turbo or supercharging your vehicle, you might  want to consider swapping your 1 bar MAP sensor to a 2 bar or 3 bar MAP sensor.

2 bar MAP sensor

This is used on vehicles that use forced induction devices such as turbochargers and superchargers. It can measure up to two times the atmospheric pressure, which is 29.4 PSI (14.7 PSI of atmospheric pressure plus 14.7 PSI from the turbo or supercharger boost). 2 bar MAP sensors are typically standard equipment in turbocharged or supercharged production models.

3 bar MAP sensor

Fitted on high-powered vehicles from the factory, 3 bar MAP sensors can measure up to 44.1 PSI (atmospheric pressure included). This means that it can read an additional 29.4 PSI boost from certain forced induction setups.

Keep in mind that using the wrong MAP sensor would affect your vehicle’s performance as the ECU wouldn’t be able to control the amount of fuel to spray into the chambers. Using a 2 bar MAP sensor on a setup that reaches 44.1 PSI will only read 29.4 PSI. Therefore, the ECU will not be able to adjust the fuel injection to match the excessive air entering the engine.

All MAP sensor identifications share a common pinout style, though the arrangement may vary depending on the part manufacturer’s design. One pin is for ground, the other should be for the sensor output or signal, and the last one is for the constant voltage which is +5 V.

Poor fuel economy and failed emission inspection

Any issue in the system that’s causing a misread can potentially compromise your car’s fuel economy. If the MAP sensor fails to send the right signal to your car’s computer, fuel will not be calibrated to match the amount of air being supplied to the engine. 

If the ECU assumes a high load in the engine, it might allow the injectors to spray more fuel than what’s needed, therefore causing excessive fuel consumption. This also has the potential to increase the emission since the engine won’t be able to burn some of the fuel. Unburnt fuel consists of hydrocarbon, carbon monoxide, and nitrogen oxide which are very harmful to humans.

Decrease in power

Lack of power due to a failing MAP sensor is the counterpart of increased fuel consumption. If the ECU reads a high vacuum, it proceeds to cut the fuel injection and relaxes the spark timing. This reduces the power output and, on the bright side, reduces fuel consumption as well. Reduced fuel economy comes with a bitter price as your vehicle would most definitely be underpowered.

Rough idling, stalling, and starting difficulty

Issues like bad idling, stalling, and starting your car all boil down to lean or excessively rich mixture being supplied in the engine. Rough idling happens when the engine starves out of fuel due to insufficient fuel injection. Stalling may also occur when the fuel and air mixture inside the cylinders become too lean. Too rich and the car might not start, especially in cold weather.

Illuminated malfunction indicator lamp (MIL)

Lastly, the check engine light or malfunction indicator lamp will be engaged. This warning light on your instrument cluster is meant to warn you about ongoing issues that relate to the engine. The aforementioned problems may arise if (1) your MAP sensor is malfunctioning or (2) the MAP sensor is completely dead.

A dead MAP sensor will not send any signal to your ECU while a failing MAP sensor would tend to send irregular signals. The MIL could indicate more problems other than the MAP sensor so visit your mechanic right away if this warning light goes off. 

OE MAP sensor replacements on CarParts.com typically cost anywhere between $2 and $280. Take note that these are exclusive prices from our website and you may find higher price tags in the market. OE MAP sensor replacements are sold in solo pieces and as part of a kit. To search for a specific MAP sensor that fits your vehicle, simply indicate its year, make, and model on the filter tab.

The manifold absolute pressure (MAP) sensor greatly contributes to the functionality of your internal combustion engine. This component measures the air pressure inside the intake manifold, signaling the engine control unit (ECU) to make the necessary changes in ignition timing and fuel injection. 

A MAP sensor is very vital, and if it were to malfunction, then your vehicle's performance would greatly suffer. In fact, severe sensor damage may prevent your ride from working at all. To remedy such problems, you should replace your busted MAP sensor with a new one right away. Lucky for you, doing so won't take up much of your time and won't cost you big bucks. In fact, all you need are some basic tools and good old fashioned elbow grease and you're good to go. So follow the steps listed below to get your ride back into fighting form.

Difficulty level: Easy

What you'll need:

• Safety gloves and goggles
• Socket set
• Replacement MAP sensor

Step 1: Before getting started, put on some safety gloves and goggles to prevent any unwanted mishaps.

Step 2: Unplug the wiring harness connector of the MAP sensor by prying the tangs on the side of the connector. You can do this with your bare hands, but you may opt to use pliers.

Step 3: Using the necessary socket, remove the retaining bolts and pull the sensor off the engine.

Step 4: Bolt the replacement MAP sensor onto the block and tighten the bolts. Be sure not to over-tighten the bolts because doing so can damage the sensor.

Step 5: Plug the wiring harness connector. See to it that the plug snaps into place and that the tangs sit firmly on the plug.

Tips

• It’s also recommended that you replace the vacuum hose that connects the MAP sensor to the engine.
• If the same problems persist, such as poor vehicle performance or unresponsive engine, then return your MAP sensor to the manufacturer or consult a mechanic.