The MAF sensor is the Mass Airflow Sensor. It reads the amount of air entering the engine.
What happens if I unplug my MAF sensor?
- When you unplug the MAF sensor, the check engine light can come up.
- Unplugging the MAF sensor could also fix the car problem – If this happens, it means that the MAF sensor is faulty and needs cleaning or repair, or replacement.
When the MAF is unplugged, The ECU uses stock factory settings to calculate air to fuel ratio. This is safe/limp mode.
You should not drive the car long when the MAF sensor is unplugged.
If the car doesn’t work properly even after unplugging the MAF sensor, it could mean that some other sensor or component is the real cause of the problem.
What actually is MAF Sensor?
The ECU/ECM/PCM needs to know the amount of air entering the car engine. ECU/ECM/PCM asks the MAF sensor to give the reading of the amount of air entering the engine. The air to fuel ratio should always be optimal for good engine performance.
The air to fuel ratio is a fixed number for your car and is known to the ECU.
With the air quantity reading provided by the MAF sensor and the known optimal air to fuel ratio, the ECU / ECM can calculate the amount of fuel needed to be allowed for the optimal combustion process.
Your ECU uses the data collected from the MAF sensor and O2 sensor to determine how much fuel to inject into the engine cylinder.
An engine control unit (ECU), controls a series of actuators on an internal combustion engine (ICE) to ensure optimal engine performance.
The ECU is also known as the Electronic Control Module (ECM). It is also known as the powertrain control module (PCM). The ECU is your car’s brain. It manages the engine, transmission, and other systems based on data received from a variety of sensors.
The MAF, having a full form of Mass Airflow sensor, is one such sensor.
When Should I disconnect my MAF sensor?
You can unplug the MAF sensor when your car shows the following symptoms :
Engine Light is on
Your check engine can come on the dashboard. The scanner shows a code that points toward a faulty MAF sensor.
Hard Start and rough idle
The car starts after multiple attempts or does not start or stalls after starting.
Malfunctioning MAF sensor gives incorrect less than actual air quantity reading to the ECU. The ECU sees less air reading, so it adds less fuel to maintain the air-fuel ratio.
Now in reality – it has more air and less fuel. Less than the required fuel is allowed by the ECU
This results in misfiring causing a hard start. This misfiring can also cause rough idle.
In this case, the car vibrates more, hesitates, and jerks during acceleration.
Fuel Inefficiency and black smoke
Malfunctioning MAF sensor gives incorrect higher than actual air quantity reading to the ECU.
ECU thinks More air – More fuel. In reality, there is less air – More Fuel. This results in poor fuel economy. You get lower mileage.
The unburnt excess fuel can also result in black smoke and poor emissions.
Does my car run better with MAF unplugged?
If your car is running better when the MAF sensor is unplugged, it means that the MAF sensor is not giving proper data to the ECU and you need to clean, repair or replace the MAF sensor.
When the MAF sensor does not give any data to the ECU, the stock factory settings are used to calculate the air to fuel ratio and so the car works better without the malfunctioning MAF sensor.
However, you need to clean, repair or replace the MAF sensor before you can drive long distances.
DO not drive long distances with the MAF sensor unplugged. It is best to fix the MAF sensor before going out for a drive. Get in touch with a mechanic near you if you need assistance in fixing the MAF sensor.
How long can I drive with the MAF sensor unplugged?
It is not advisable to drive for a long time with the MAF sensor unplugged. You run the risk of failing an emission test and incurring a fine.
When the MAF sensor is unplugged, the ECU/ECM uses stock factory settings data to determine how much fuel needs to be injected into the engine cylinder. The engine runs fine. However, the stock factory settings data is assumed data for a new car.
In reality, the actual data is not provided by the MAF sensor as it is unplugged.
If the MAF sensor is not working properly, you need to clean or repair or replace it. If you need assistance, you can contact a local mechanic to help you with fixing the MAF sensor.
To clean the MAF sensor of accumulated dirt – you need to first disconnect it.
How do I disconnect the MAF sensor?
The mass airflow sensor is located between the air filter box and the engine’s intake manifold. The MAF sensor is placed in plastic housing.
There are two types of MAF sensors:
- Hot Wire Type MAF sensor
- Hot Film MAF sensor – This is the more modern version. It does not have platinum wires but has a sensor plate instead.
For safety precautions, You can wear safety gloves, disconnect the battery, and turn the engine off.
After that, You can just pull out the electric cord of the MAF sensor.
Then use a screwdriver to unmount the MAF sensor.
You can then use MAF sensor cleaner spray on the holes to clean the sensor. Let it dry for some time and then plug it back in.
If the car problem is still not fixed then replace the sensor and try once.
How do I clean the MAF sensor?
Dirt accumulates on the MAF sensor and it is present in the airflow path. The MAF sensor gets dirty due to the fine dust particles that go past the air filter. As time passes the dirt builds up causing a sensor to stop working correctly.
Cleaning the MAF sensor is easy with the right supplies.
You need to get the right MAF sensor cleaner spray.
You can follow the below checklist to clean the MAF sensor:
- Switch off the engine of your car.
- Disconnect the battery as a precaution.
- Unplug the MAF sensor by removing the electric chord.
- Unscrew the MAF sensor with a screwdriver.
- Wear hand gloves, eye protection, and a mask to stay safe from chemicals in MAF sensor cleaner spray.
- Use the MAF sensor cleaner spray. Connect the straw to the MAF sensor cleaner spray bottle.
- Spray short bursts on the holes and the hot wires of the MAF sensor.
- Keep the straw of the spray at a distance from the MAF sensor
- Spray all sides and holes.
- Allow the MAF sensor to dry well for more than thirty minutes.
- Plug the sensor back in, and screw it with the screwdriver to mount it.
- Connect The Battery, Start the Engine.
See if the car problem you were facing is solved now. Check the engine light on the dashboard. You can also use a scanner to see if any codes come up.
If you are looking for a MAF sensor cleaner, CRC mass airflow sensor cleaner is the most popular option on the market. You can check it out on Amazon
How to replace the MAF sensor?
The cost of a new MAF sensor is between $30 to $300
Start by locating the existing MAF sensor and disconnect. It is located between the air filter box and the intake manifold of the engine.
The OEM part number could also be written on your existing MAF sensor.
You can visit automobile parts websites or apps. Enter your vehicle’s year, make, and model to find the part number of your vehicle’s MAF sensor. After fitting the new MAF sensor, make sure the air filter box is closed properly.
Check whether the engine light is not shown on your dashboard. If you need assistance, please contact a local car mechanic.
What happens when the MAF sensor does not work correctly?
When the MAF sensor doesn’t work properly, one of the below three cases arises:
1) The MAF sensor gives an incorrect lower than the actual reading of air quantity to the ECU.
ECU knows the optimal air to fuel ratio. ECU sees low air quantity reading so it allows low fuel to maintain air to fuel ratio. In reality, more air is entering the engine and less fuel is allowed by the ECU. As ECU allows lower than required fuel for combustion – hard start, and rough idle problems arise.
2) In the opposite case, The MAF sensor gives an incorrect higher than the actual reading of air quantity to the ECU.
ECU sees high air quantity reading so it allows high fuel to maintain air to fuel ratio. In reality, less air is entering the engine and more fuel is allowed by the ECU.
As ECU allows higher than required fuel for combustion – Fuel Inefficiency, Black Smoke problems arise.
3) The MAF sensor stops working and gives no reading.
In this case, the ECU relies on stock factory settings data. The engine continues to work. This is safe/limp mode and the car should not be driven with an unplugged MAF sensor for a long time.