MAF Mass Airflow Sensor Common Symptoms and Troubleshooting
This short guide can help you diagnose common drivability issues that can be caused by a defective MAF sensor, and either confirm it is a mass airflow sensor fault or some other underlying issue.
- Most common problems associated with your mass airflow MAF sensor and how to overcome them
- How to find out if your MAF sensor is responsible for poor running issues
Topics in This Blog
- What is a MAF mass airflow sensor and how does it work
- Symptoms often associated with a defective or dirty airflow sensor
- Installing a new MAF sensor
- Common effects of a bad MAF sensor
Common symptoms of a defective or dirty MAF sensor
If you have one or more of the following symptoms, it could be your mass airflow sensor at fault.
- Reduced or flat engine power
- Poor idling and engine vibration, and or surging
- Hesitating or stalling during acceleration
- Reduced fuel efficiency
- Other driveability issues
- Diagnostic trouble codes suggesting MAF sensor fault
Depending on vehicle models, the mass airflow sensor will report to the ECU on factors like air intake temperature and engine load etc, A defective MAF sensor on these cars can cause a wider range of symptoms.
You cannot diagnose a MAF sensor issue based on symptoms alone, because other faulty components including but not limited to the fuel pump, fuel pressure regulator, vacuum system and others can create similar symptoms.
You need to troubleshoot the MAF sensor and related circuits before replacing the actual sensor, sometimes it can boil down to a process of elimination.
How does a mass airflow sensor work?
In basic terms, the mass airflow sensor (MAF) measures the volume, temperature and density of air flowing into the engine through the air intake and filter assembly.
The information provided by the MAF sensor is absolutely crucial to the efficient operation of your engine and as such any incorrect information provided by your vehicles, MAF sensor can dramatically affect performance and fuel efficiency.
Your vehicle will use either a hot-wire airflow meter or a hot-film type (hotwire MAF are most common).
Only different by design, but still the same function.
The hot wire type MAF uses a wire positioned in the middle of the airstream and at a higher temperature than the air flowing in.
So that the predetermined temperature can be maintained, the electric current to the wire increases as airflow increases.
The hot-film type MAF operates essentially the same but simply uses a film, rather than wire.
The information provided by the mass airflow sensor is fed, with input from other sensors, to the vehicle's computer (ECU) which in turn calculates various factors including the correct amount of fuel to the engine at any given time.
What will cause A MAF sensor to fail
The most common cause of MAF sensor failure is a dirty sensing element, if the hot wire or film element is dirty or damaged it will not be able to correctly sense airflow, which will result in a range of running issues.
Cleaning The Airflow Sensor – Caution They Can Be Easily Damaged
Using sensor cleaning spray is the best way to attempt cleaning the sensor but be very careful not to damage it by touching the actual element with rags, cotton earbuds or indeed cleaning agents not intended for MAF sensor cleaning.
Air Leaks and Contamination.
An air leak around the air filter housing, a crack or improperly installed filter cover will allow unfiltered air into your air intake system and result in contamination of the sensor element.
If there are no air leaks and you have cleaned your MAF, but you want to be 100% you might need an auto electrician to test voltage levels prior to buying and fitting a new airflow sensor.
New MAF Sensor
In most modern vehicles replacing the mass airflow sensor is not technically difficult, but as with anything, if you are not sure, hire a professional to do it for you (it could save you a lot in the long run)
Always opt for the manufacturers supplied parts, even parts that are sold as compatible often do not perform as well as OEM.
Replacing the MAF Yourself
- Disconnect the part of the air intake duct that houses the MAF sensor
- Carefully unplug the electric sensor connector
- Unscrew two or more hex bolts holding the sensor in place
- Remove the old sensor and install the new one
- Replace hex bolts
This blog is accurate and true to the best of the author’s knowledge. Content is for information only and we recommend you seek professional advice on all technical matters.