Symptoms of a faulty map sensor

In contemporary engines, the mass airflow (MAF) or manifold absolute pressure (MAP) sensors are used to detect or compute air flow by the engine control module (ECM). While naturally aspirated engines typically employ one or the other, turbocharged engines may use both. The ECM, and consequently the engine, cannot operate properly if the MAP sensor is malfunctioning or damaged.

The main purpose of the MAP sensor, which is present in fuel-injected automobiles, is to tell the Powertrain Control Module (PCM/ECM) about the pressure in the intake manifold. The MAP sensor will experience wear and tear and damage over time, just like every other sensor in your car, which could result in inaccurate data being sent to the engine management module. Thus, in this article, we’ll be discussing the following;

symptoms of a faulty map sensor

  • How does the map sensor work?
  • Where is the map sensor located?
  • Symptoms of a faulty map sensor.
  • What are Map sensor problems?
  • What are the Causes of a Faulty MAP Sensor?
  • How do you troubleshoot a map sensor?
  • Map sensors replacement.
  • How Much Does a MAP Sensor Replacement Cost?

So, let’s dive in!


How does the map sensor work?

Important calculations including engine load, fuel injector pulse, and spark advance are performed by the ECM using data from the MAP sensor. The MAP sensor measures atmospheric pressure at sea level (29.93 in. Hg) when it is at rest. The ECM determines this “zero” position shortly before the engine begins, fine-tuning the spark and fuel injection mapping from there because atmospheric pressure fluctuates with weather and altitude.

Intake pressure during idle typically ranges from 16 to 22 inches of mercury. Air rushes into the intake because this is lower than atmospheric pressure. Pressure can drop as low as 10 in. Hg when the driver applies the brakes with the engine. However, as the vehicle accelerates, the open throttle body allows air to enter more quickly and raises intake pressure. Intake and ambient pressure are almost equal at wide-open throttle.

Where is the map sensor located?

The MAP sensor is normally found on or near the throttle body on the intake manifold. The MAP sensor is located on the intake tract before the turbo on a forced-induction engine. A sealed chamber with either a vacuum or a controlled pressure that is calibrated for the engine is located inside the MAP sensor. A flexible silicon wafer, often known as a “chip,” with a current flowing through it separates the vacuum from the sensor and the vacuum from the intake manifold.

Symptoms of a faulty map sensor

Failure of MAP sensors is caused by clogging, contamination, or damage. Sometimes, the heat from the engine “overcooks” the MAP sensor’s circuitry or damages the vacuum lines. If the MAP sensor malfunctions, the ECM won’t be able to determine engine load effectively, which will result in an air-fuel ratio that is either too rich (more fuel) or too lean (less fuel).

So how will you be able to tell when your MAP sensor is failing? The following are the symptoms of a faulty map sensor;

  • Check engine light is on.
  • Low power.
  • Failed emission test.
  • Poor fuel economy.
  • Lean and rich air-fuel mixture.
  • Problem starting.
  • Rough idling.

Check engine light is on

The diagnostic trouble codes (DTC) for your MAP sensor might indicate anything from simple circuit, sensor, or range errors, depending on how old your car is. A malfunctioning MAP sensor may provide the ECM with data that is illogical, such as low engine vacuum, when the crankshaft position sensor (CKP) and the throttle position sensor (TPS) both indicate the engine is running at idle. A dead MAP sensor won’t read anything.

Map sensor fault codes

If your check engine light has illuminated, look for the following codes linked to the MAP sensor:

  • P0105: MAP Circuit Malfunction.
  • P0106: MAP/Barometric Pressure Circuit Range/Performance Problem.
  • P0107: Manifold Absolute Pressure/Barometric Pressure Circuit Low Input.
  • P0108: MAP Pressure Circuit High Input.
  • P0109: MAP / Baro Pressure Circuit Intermittent.
  • P1107: Barometric Pressure Sensor Circuit Low Voltage.
  • P0068: MAP/MAF – Throttle Position Correlation.
  • P0069: Manifold Absolute Pressure – Barometric Pressure Correlation.
  • P1106: MAP/BARO Pressure Circuit Range/Performance Problem.

These codes can occasionally be set by other sensors or other malfunctioning components. Even if your engine is exhibiting the aforementioned symptoms and is flashing one or more of the above OBD-II codes, it is advised to test the MAP sensor to make sure it is broken.

Low power

The ECM lowers fuel injection and delays spark timing if it detects high vacuum because it believes the engine load is low. On the one hand, the reduction in gasoline use appears to be a good thing. But if too little fuel is used, the engine does not have the power to accelerate and pass.

Failed emission test

An increase in hazardous emissions can result from a faulty MAP sensor because fuel injection doesn’t match the engine load. Higher hydrocarbon (HC) and carbon monoxide (CO) emissions are produced by using more gasoline, while higher nitrogen oxide (NOx) emissions may result from using less fuel.

Poor fuel economy

The ECM increases spark timing and adds additional fuel if it detects low or no vacuum because it believes the engine is under heavy load. This results in high gasoline use, poor fuel efficiency, and perhaps detonation.

Lean and Rick air-fuel mixture

The main function of the MAP sensor is to detect the air pressure in the intake manifold and determine the ideal air-fuel ratio for your engine. Your engine may run with an excessively lean air-fuel combination if the sensor is malfunctioning. Below is a list of odd symptoms that your engine may experience as a result of a lean fuel mixture.

The same holds true for the reverse as well. The engine control unit may inject too much fuel into the car engine if the MAP sensor is damaged because it can potentially send an incorrect signal. Your fuel consumption will increase due to a rich air-fuel mixture, which will also affect performance.

Problem starting

Similar to this, an excessively rich or lean mixture makes starting the engine challenging. You most likely have a MAP sensor issue if the engine will only start when the accelerator is depressed.


Stepping on the gas when starting from a stop or attempting a passing move may not be fun, especially if the ECM is feeding you a lean mixture based on inaccurate MAP sensor readings.

Rough idling

Inadequate fuel injection depletes the engine’s fuel supply, causing rough idling and possibly even sporadic cylinder misfiring.


When the combustion process inside the engine cylinder fails, misfires happen. A poor spark or an incorrect air-fuel ratio may be to blame for this. In fact, a MAP sensor may make the air-fuel combination so poor that misfires become noticeable. Misfires are frequently detectable by simply listening to your engine. Misfires may be to blame if you hear minor bumps or if the sound is different from how it generally sounds.

What are Map sensor problems?

An essential component of your vehicle’s upkeep is a working MAP sensor. The following components should be checked first if you think your MAP sensor may be malfunctioning. The following are map sensor problems;


Some MAP sensors have a hose that connects them to the intake manifold. Verify that the MAP sensor hose is attached and in good condition. Additionally, make sure the port is free of any carbon buildup or other debris that can obstruct the hose and result in inaccurate readings from the MAP sensor.


Start by looking at the wire and connector. The pins should be neat and straight, and the connector should be properly attached. MAP sensor signal issues might be brought on either by corrosion or bent pins. The connection between the ECM and MAP sensor ought to be in good condition as well. Chafing and fractures may result in short circuits and open circuits, respectively.


Use a scan tool, voltage meter, and vacuum gun to examine the output of the MAP sensor to ensure that it is electrically and mechanically linked to the intake manifold properly. You’ll need to find a chart to compare voltage against both a vacuum of no air and a vacuum of all air. It is safe to assume that the sensor has to be changed if the MAP sensor output does not match the chart.

What are the Causes of a Faulty MAP Sensor?

  • Contamination is brought on by engine deposits like carbon.
  • The sensor’s capacity to detect pressure changes is compromised by a clogged or leaky hose.
  • Electrical connectors that have become loose, melted, or broken as a result of overheating from being close to the engine.

How do you troubleshoot a map sensor?

Examine the MAP sensor’s physical condition before beginning any tests. To start, make sure there are no loose connections and inspect the connector and wiring for any damage, such as burnt or cracked wires. Check the pins after disconnecting the sensor; they should be clean, straight, and free of corrosion or bending.

The hose (if applicable) that connects the sensor to the intake manifold should next be checked for any signs of damage and to ensure that it is tightly connected to the sensor. Last but not least, check the hose’s interior to make sure it is clean.

Using a digital multimeter set to 20V and a vacuum pump, you can test the MAP sensor if everything passes the physical examination.

Map sensors replacement

  • The MAP sensor should be located on the intake manifold, either there or right next to the throttle body.
  • Any bolts or screws keeping the sensor in place should be removed.
  • The electrical connector should be disconnected. Avoid removing the connector by force since it can have a locking tab that needs to be pulled out in order to free the connector from the sensor.
  • Remove the vacuum hose from the sensor, if necessary. When changing the sensor, it is advised to also change the vacuum hose.
  • The new and old sensors are compared.
  • Reconnect the suction hose if necessary.
  • Reconnect the electrical connector for the sensor.
  • Any bolts or screws holding the sensor in place should be replaced.
  • Verify that all connections are secure by checking them twice.

Please refer to the manufacturer’s service manual for your vehicle for any particular instructions on how to replace a bad MAP sensor. After the defective sensor has been taken out, installing the replacement component is simple. The check engine light could need to be reset with a diagnostic tool, depending on the car and whether a fault code was set.

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How Much Does a MAP Sensor Replacement Cost?

Depending on the automobile model and labor expenses, the average cost to replace a MAP sensor ranges from $60 to $170. The cost of labor ranges from $30 to $70, and the sensor itself is priced between $30 and $100.

On most car models, changing the MAP sensor is typically rather simple and may be done by the owner at home. You may easily save money by doing it yourself if you know a little about cars.


How do I know if my MAP sensor is bad?

  • Look for rough idling, poor fuel economy, slow acceleration, and a strong gasoline odor (particularly at idle). Rich air-fuel ratio.
  • Look for surging, stalling, a lack of power, hesitancy when accelerating, backfiring via the intake, and overheating to indicate a lean air-fuel ratio.

What happens when the MAP sensor goes bad?

Because the ECM cannot accurately determine the engine load, a defective MAP sensor will limit its capacity to modify the air/fuel ratio and ignition timing. An abnormally rich or weak air-fuel combination may arise from this.

What happens if you unplug the MAP sensor?

The engine control unit (ECU) will stop receiving data regarding the pressure within the intake manifold if you unplug the Manifold Absolute Pressure (MAP) sensor. The ECU won’t be able to determine the right amount of fuel to inject into the right amount of air for combustion as a result.

Does the MAP sensor affect timing?

It is possible for a defective Map Sensor to make a car run rich or lean, which will disrupt the ignition timing and make the engine operate poorly.

Is it okay to clean a MAP sensor?

The MAP sensor may need to be cleaned if it has become polluted by carbon or other engine deposits even though it has no moving parts and rarely has to be replaced. Contamination may be to blame if voltage reacts slowly to changes in pressure.

How do you reset a MAP sensor?

Look over the MAF sensor and blow it dry. After 12 minutes, reconnect the battery and turn it on again. The computer will no longer be motivated to learn new things. Next, take the car for a spin to see what occurs.

Does the MAP sensor affect idle?

Engine rpm might fluctuate or spike as a result of a bad map sensor, especially at idle or low speeds. The engine may shut off if the power steering or air conditioning is turned on at that time.

What does the MAP sensor detect?

The sensor instantly informs the engine’s electronic control unit of the manifold pressure. The information is put to use to compute air density and figure out the engine’s air mass flow rate, which in turn figures out how much fuel is needed to achieve complete combustion.

Can I run a car without a MAP sensor?

Yes, it is possible to drive without a MAP sensor, however, it is too dangerous. If the pressure sensor is detached as a result of excessive fuel delivery, the engine and exhaust system may sustain damage.

What is the difference between a MAP sensor and an MAF sensor?

The amount of air the engine produces is measured by an MAF sensor. On the other hand, a MAP sensor provides a reading of the air pressure in the intake manifold. This data is used by the ECU to determine how much air needs to be inhaled.

What happens when intake manifold pressure is low?

The ECM will assume that the engine load is high if it detects low intake manifold pressure as a result of problems like a vacuum leak and will send more fuel to make up for it. This results in high fuel use and low fuel efficiency.

That’s all for this article where we discussed the following;

  • How does the map sensor work?
  • Where is the map sensor located?
  • Symptoms of a faulty map sensor.
  • What are Map sensor problems?
  • What are the Causes of a Faulty MAP Sensor?
  • How do you troubleshoot a map sensor?
  • Map sensors replacement.
  • How Much Does a MAP Sensor Replacement Cost?

Hope it was helpful. If so, kindly share. Thanks for reading.

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