Symptoms of a Bad or Failing Mass Airflow Sensor

Schedule Vehicle Engine Mechanical Inspection
Service Area

$0.00

Upfront, Transparent Price
Average rating from 134,456 customers who received a Vehicle Engine Mechanical Inspection.

Mass Airflow Sensors (MAF) have the responsibility of reporting the amount of air entering the engine to the Powertrain Control Module (PCM). The PCM uses this input to calculate engine load.

There are several designs of MAF sensors, but the most common by far is the hot wire MAF sensor. The hot wire MAF has two sensing wires. One wire is heated and the other is not. The microprocessor (computer) inside the MAF determines the amount of air entering the engine by how much current is required to keep the hot wire about 200 ℉ hotter than the cold wire. Whenever the temperature difference between the two sensing wires changes, the MAF will either increase or decrease the current to the heated wire. This equates to more air into the engine or less air into the engine.

There are a number of driveability issues that arise from faulty MAF sensors.

1. Runs rich at idle or lean under load

These symptoms indicate a MAF that has a contaminated hot wire. The contamination can come in the form of spider webs, potting compound from the MAF sensor itself, dirt that gets attached to oil on the MAF from an over-oiled aftermarket air filter, and more. Anything that acts like insulation to the hot wire will cause this type of issue. The fix is as simple as cleaning the MAF sensor with an approved cleaner, which the technicians at YourMechanic can do for you if they determine that this is the root problem.

2. Constantly runs rich or lean

A MAF sensor that continuously over-reports or under-reports airflow into the engine will cause an engine to run rich or lean. If the engine control system is working correctly, you will probably never notice this except for a change in fuel economy. A trained technician will have to look at fuel trim status with the use of a scan tool to verify this. A MAF sensor that behaves like this will require replacement. Before replacing the sensor, however, the rest of the circuit should be checked for proper operation. If the circuit has an issue, replacing the sensor will not solve your problem.

3. Rough idle or stalls

A completely failed MAF sensor will not send any airflow information to the PCM. This prevents the PCM from accurately controlling fuel, which will result in an engine that either will idle roughly or not at all. Obviously, replacing the MAF sensor is needed in this case.


Next Step

Schedule Vehicle Engine Mechanical Inspection

The most popular service booked by readers of this article is Vehicle Engine Mechanical Inspection. Yourmechanic’s technicians bring the dealership to you by performing this job at your home or office 7 days a week between 7AM-9PM. We currently cover over 10k cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Vehicle Engine Mechanical Inspection reviews

Excellent Rating


YourMechanic Vehicle Engine Mechanical Inspection Service

Average Rating

4.9/5

Number of Reviews

134,456

Rating Summary
125,658
4,892
972
681
2,253
125,658
4,892
972
681
2,253

Raymond

36 years of experience
173 reviews
Raymond
36 years of experience
Cadillac Brougham - Vehicle Engine Mechanical - Las Vegas, Nevada
Talent and passion for what you do in any field is critical, Raymond seems to have both. I have dealt with many Mechanics in my day Raymond is one of the best. Thank you sir.
Jeep Grand Cherokee - Car is not starting - Las Vegas, Nevada
Raymond showed up early and found the problem fairly quickly and took care of it in a professional timely manner

Alex

15 years of experience
435 reviews
Alex
15 years of experience
Ford Expedition - Battery - Irving, Texas
Good job on time and kept us informed of arrival times and efficient and well done
Oldsmobile Alero - Car is shaking or vibrating - McKinney, Texas
Very professional and took time to help troubleshoot my car ive already set up my next appointment..

Oswaldo

21 years of experience
28 reviews
Oswaldo
21 years of experience
Hyundai Sonata - Starter - Edison, New Jersey
Great service and effort. I would recommend him for sure.

Jerome

23 years of experience
415 reviews
Jerome
23 years of experience
Hyundai Sonata - Ball Joint Front Replacement (Lower Right) - Windsor Mill, Maryland
Jerome took great care of my vehicle. It was a wonderful experience.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE