SYMPTOMS OF A BAD MASS AIRFLOW SENSOR
purpose
The purpose of the Mass Airflow Sensor (also known as a MAF sensor) is to read the amount of air coming into the engine. The ECM then uses this data to calculate the best air-fuel ratio for the combustion.
location
The MAF sensor will typically be located on the air intake before the throttle. Not all cars have a mass airflow sensor, yours might come with a MAP sensor, instead. If your vehicle has a MAP sensor, then you need to check out my video on the Symptoms of a bad MAP sensor.
symptoms
engine light
The easiest way to figure out if your MAF sensor is bad is by noticing if the check engine light is on. Here are some codes related to a bad mass airflow sensor:
P0100
P0101
P0102
P0103
P0104
Ensure you can access your car's diagnostic codes by acquiring an OBD2 scanner here.
There are times when the engine light doesn't come on but the sensor is still faulty, so let's move on to the next symptom of a bad MAF sensor.
no start
The second symptom of a bad MAF sensor is a no-start. If the MAF sensor is giving the wrong reading of less air coming in, then the ECM will command less fuel. But in reality, there's more air coming in, so the ECM should have been commanding more fuel. This results in more air than fuel ratio, which causes poor combustion and gives us a no start.
rough idle
The third symptom you might be experiencing with your car is a rough idle. Let's say your car starts at odd times and you drive it only to figure out that you feel your car shaking when it's at a stop sign or a red light. The reason for this could be the same factor the ECM is getting a faulty reading of less air coming in, therefore, it commands less fuel. However, a good working MAF sensor should have been reading more air, so it should have been adding more fuel. This results in more air than fuel, which leads to poor combustion efficiency with a couple of misfires. This is why you’re experiencing a rough idle.
bad fuel economy
The fourth symptom you might be experiencing with your car is bad fuel economy. Now let's flip the script here and say the MAF sensor is giving the ECM a faulty reading of more air coming in. This will result in the ECM commanding more fuel. However, the real reading should have been less air coming in, so the ECM should have been commanding less fuel. Since the ECM got tricked by a faulty MAF sensor, as a result, there will be more fuel than air ratio, which means the ECM is using more fuel than what is needed this can be the reason why your fuel economy has been suffering.
black smoke
The last symptom is black smoke coming from the exhaust. Due to the previous example of more fuel being used than what is needed the leftover fuel gets kicked out of the exhaust, which gets burned and turns into black smoke.
If the MAF sensor in your car is dirty, instead of buying a new one you can try cleaning it yourself. Buy my favorite Mass Airflow Cleaning Chemical here.
Check out my YouTube video!
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