MAF, or mass airflow sensor, is an important part of engine combustion. It works with the ECM to provide the idle combustion process that drives the engine. Mass airflow sensors may become dirty or wear out over time. It can easily last up to 100,000 to 125,000 miles without major issues.
Rough idle, hesitation, stalling, and bad fuel economy are some symptoms of bad MAF sensors. However, you can’t be sure by looking for one symptom. Confirm at least two or three symptoms to be sure.
MAF sensor issues may damage the engine, so maintain it over time. Cleaning and resetting the sensor solves most of the problems. I have talked about six MAF sensor symptoms, a few problems, their solution, resetting the sensor, etc, in this article.
Symptom 1: Rough Idle
A bad air-to-fuel mixture causes the engine to idle roughly. Rough idling of vehicles generally indicates engine issues. You can check the RPM of your car while idling.
If it fluctuates, the mass air flow sensor may have a problem. Your vehicle engine will vibrate much more than usual if roughly idling.
Solution: The sensor may become clogged or dirty, causing faulty readings. Cleaning the sensor may solve the rough idling issue. You will need to reset or replace it if it’s not dirty.
Symptom 2: Accelerating Hesitation
Faulty mass airflow sensors fail to maintain the usual fuel-to-air ratio. Generally, a 14.7L air to 1L gasoline ratio is ideal.
The engine will hesitate during acceleration if there is more or less air. You will face the issue during acceleration and may face stalling.
Solution: You must clean the sensor, as faulty air flow readings may cause hesitation. Sometimes, you need to reset the sensor, which will fix the issue.
Symptom 3: Sudden Stall
Sudden stall is another symptom of a bad MAF sensor. If the air-to-fuel ratio is not right, the engine might suddenly misfire and stall.
It generally happens after a while of engine start. Though restarting the engine solves the issue temporarily, it may happen repeatedly.
Solution: Sudden stall is an indication of MAF sensor failure. Replacing the current sensor will be a good solution.
Symptom 4: Misfire
The engine may misfire due to a faulty mass airflow sensor. It mainly occurs due to faulty air in the engine. If the air is low compared to the fuel, it will cause misfires.
It may also lead to vehicle stalling and put your vehicle into limp mode. It is not the only indication of a faulty MAF sensor, and you should look out for other symptoms to be sure.
Solution: If the MAF sensor causes your engine to misfire, you must diagnose the spark plugs. If they are ok, then the problem is with the MAF sensor. It may need cleaning or reset to solve the issue.
Symptom 5: Poor Fuel Economy
The ideal ratio of air and fuel is important for usual combustion. Too much air will cause rich combustion, and too little air will cause poor combustion in the engine. A bad MAF sensor will cause poor fuel economy of the engine. It is a common indication of a bad mass airflow sensor.
Solution: It is an indication of MAF sensor failure. There can be other factors like fuel pump, spark plug, ECM issues, etc. If these are ok, then the mass airflow sensor is faulty. Repair or replace it to solve the problem.
Symptom 6: Check Engine Light
Check engine light, which will illuminate if your engine has problems. Mass airflow sensor causes hesitation, rough idle, misfire, and other issues with the engine, which causes the check engine light to illuminate.
When the ECU finds a problem, it turns on the light. You may also notice the limp mode light to be on due to a faulty MAF sensor.
Solution: Scan the vehicle with an OBD-II scanner. The MAF sensor-related trouble codes are P0100 to P0104 and P0171 to P0174. If there is a voltage issue, you must replace the sensor. If the problem is with faulty reading, it may need cleanup and calibration.
Common MAF Sensor Problems
Common MAF sensor problems are:
- Hard start: MAF sensor issues cause the engine to hard start.
- Smoke: Low air ratio causes smoky combustion and darker exhaust smoke. It is a common problem with faulty mass airflow sensors.
- Stalling: Sudden or permanent stalling is common for vehicles with an MAF sensor
- Vibration: A hard start and rough idle cause the vehicle to vibrate more.
- Low fuel economy: Fuel economy becomes low due to bad combustion. Faulty MAF sensor is responsible for that.
- Bad performance: Bad combustion leads to bad performance of the vehicle due to a faulty MAF sensor.
Can You Drive with a Bad Mass Air Flow Sensor?
The mass airflow sensor controls the airflow to the engine. ECU controls the air-to-fuel ratio in the engine for combustion. 14.7L air is necessary to combust 1L gas. Dust or debris, electric issues, and wear cause the sensor to malfunction.
Faulty reading causes engine issues like hard start, stalling, rough idle, hesitation, bad fuel economy, performance issues, etc. Check engine light illuminates, and the vehicle may go into limp mode to avoid engine damage.
Driving with a faulty MAF sensor may damage the engine. So, it is not recommended to drive with a faulty MAF sensor. You should diagnose the issue as soon as possible. You may drive the vehicle carefully to reach a nearby mechanic shop if you are already on a trip for a solution.
How to Reset Mass Air Flow Sensor?
You can reset the mass airflow sensor by disconnecting the sensor and idling the vehicle for 10 seconds or removing the battery.
Method 1: Disconnecting the Sensor
MAF sensor generally sits between the air filter and manifold of the engine. Disconnect and remove the sensor. After that, start the vehicle and idle for more than 10 seconds. Now, clean off the sensor and reconnect it. The MAF sensor will be reset in this way.
Method 2: Disconnecting the Battery
Disconnect the battery negative terminal first and secure it. After that, disconnect the positive terminal and also ensure it. Now, turn on the headlights or honk a few times to discharge the electrical system. Wait for 10 minutes for full discharge. Now, clean and reconnect the battery terminals. Disconnect and clean the MAF sensor and reconnect it. Start the vehicle and restart the computer. It should reset the mass airflow sensor now.
FAQs
What problems can a dirty MAF sensor cause?
Dirty MAF causes rough idle, hesitation, hard start, stalling, etc. It may also cause bad fuel economy, poor performance, rich or lean running, smoke, etc. Faulty MAF sensor readings cause these issues.
ECU controls the combustion process by reading the mass air flow sensor. Dirty MAF sensors may not get the proper airflow. It causes the sensor to give faulty readings to the ECU. As a result, these issues occur on a vehicle.
How to test a mass air flow sensor?
You can test a mass airflow sensor with a multimeter or an OBD-II scanner. Use a multimeter to test the voltage of different sections of the sensor. There should be a manufacturer manual with ideal reading data.
Match the results and look out for issues. For the OBD-II scanner, look for error codes P0100 to P0104 and P0171 to P0174. If any of these codes appear, the sensor has an issue. MAF sensors are cheap, and you can easily replace them.
Can a bad mass airflow sensor cause transmission problems?
Yes, a bad MAF sensor can cause transmission issues. Transmission works with the engine to shift between gears. Engine problems also affect transmission. MAF sensors can send faulty airflow data to the computer.
Faulty data will cause the engine combustion process to become inaccurate. As the engine runs non-optimistically, the transmission may face different stability issues.
How can you tell if the MAF sensor is bad?
You can check the MAF sensor with a multimeter or an OBD-II scanner. You can also check the sensor with just the vehicle idling too. The sensors have issues if the engine runs even after disconnecting the sensor.
If the engine stalls after disconnecting the sensor, it is working. You can also check exhaust gas and spark plugs for abnormalities. Keep an eye on the fuel economy for possible symptoms.
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