The mass airflow (MAF) or manifold absolute pressure (MAP) sensors are used by the engine control module (ECM) to detect air flow in contemporary engines. While naturally aspirated engines typically use one or the other, turbocharged engines may use both. The ECM and engine cannot operate properly if the MAP sensor is malfunctioning.
Over time, the MAP sensor may experience wear and tear, resulting in inaccurate data being sent to the engine management module. The MAP sensor plays a vital role in helping the ECM determine when the ignition should occur under varying engine load conditions.
Bad MAP sensors are 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).
Well in this reading, we’ll explore the ten possible symptoms of a faulty map sensor and what causes it.
Let’s Get Started!
Contents
What are the Symptoms of a Faulty Map Sensor?
The common symptoms of a faulty map sensor include illuminated check engine light, map sensor fault codes, low power, failed emission test, poor fuel economy, lean and rich fuel air mixture, starting problem, stalling, rough idle, and misfire.
1. 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.
2. Map sensor fault codes
If your check engine light has illuminated, look for the following codes linked to the MAP sensor:
- P0068: MAP/MAF – Throttle Position Correlation
- P0069: Manifold Absolute Pressure – Barometric Pressure Correlation
- 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
- P1106: MAP/BARO Pressure Circuit Range/Performance Problem
- P1107: Barometric Pressure Sensor Circuit Low Voltage
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.
3. 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.
4. 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.
5. 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.
6. Lean and Rich 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.
7. 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.
8. Stalling
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.
9. Rough idling
Inadequate fuel injection depletes the engine’s fuel supply, causing rough idling and possibly even sporadic cylinder misfiring.
10. Misfires
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 may be to blame if you hear minor bumps or if the sound is different from how it generally sounds.
What are the Causes of 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 the common causes of map sensor problems;
Hose
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. Contamination is brought on by engine deposits like carbon.
Electrical
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. Electrical connectors that have become loose, melted, or broken as a result of overheating from being close to the engine.
Sensor
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. The sensor’s capacity to detect pressure changes is compromised by a clogged or leaky hose.
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.