The mass air flow (MAF) sensor is a critical component of the engine management system of your F-Series pickup. In this tutorial I'll answer some of the most commonly asked questions about the MAF sensor.
Contents of this tutorial:
APPLIES TO: This tutorial applies to the following vehicles:
- Ford F150: 1993, 1994, 1995, 1996.
- Ford F250: 1993, 1994, 1995, 1996.
- Ford F350: 1993, 1994, 1995, 1996.
What Does A MAF Sensor Do?
The job of the mass air flow sensor on your Ford F-Series pickup is to measure the amount of air entering the engine, as it runs, and then reporting it to the fuel injection computer.
With this information, the fuel injection computer can calculate the correct amount of fuel to inject into each cylinder.
What Happens When A MAF Sensor Goes Bad?
When the mass air flow sensor fails, it will stop measuring and reporting the amount of air that the engine in your Ford pickup is breathing.
In the next section I'll go into some of the specific symptoms you'll see when the MAF sensor fails.
What Problems Can A MAF Sensor Cause?
Since the mass airflow sensors signal is critical for engine operation, when it fails it will definitely cause engine performance and drivability issues.
You'll see one or more of the following symptoms:
- Bad gas mileage.
- Lack of power.
- Black smoke coming out of a tailpipe.
- Check engine light is illuminated by one or more MAF sensor trouble codes.
- Rough idle.
- The engine may start and immediately stall.
- Extended engine cranking (the engine has to be cranked a long time for it to start).
- The engine may not start.
- On OBD I vehicles, the check engine illuminated by one of the following trouble codes:
- 157: MAF Sensor Circuit Low Input
- 158: MAF Sensor Circuit High Input
- 159: MAF Sensor Circuit Voltage Higher Or Lower Than Expected
- On OBD II vehicles, the check engine illuminated by one of the following trouble codes:
- P0102: MAF Sensor Circuit Low Input
- P0103: MAF Sensor Circuit High Input
- P1100: MAF Sensor Output Voltage
- P1101: MAF Sensor Output Voltage
How Can You Tell If A MAF Sensor Is Bad?
The only way to be 100% sure that the mass air flow sensor is bad, without replacing, is to test it.
See the next section to find out more.
How Can I Find Out If The MAF Sensor Is Bad?
Testing the mass air flow sensor with a multimeter is a simple way to find out if it is good or bad.
Here's the basic testing procedure to follow when diagnosing the mass air flow sensor with a multimeter:
- Check for MAF sensor trouble codes with a code reader or scan tool.
- Confirm that the MAF sensor is receiving 12 Volts.
- Confirm that the MAF sensor is receiving Ground.
- Confirm that the sensor's MAF voltage signal increases/decreases as the engine is accelerated/decelerated. This test is done with a multimeter.
If the MAF voltage signal does not increase/decrease as you accelerate/decelerate the engine, then you can conclude that your F-Series pickup's MAF sensor is bad and needs to be replaced.
Testing the mass airflow sensor is something that you can do without having to take it to an automotive repair shop (but you can).
I've written a tutorial on how to test it with a multimeter, you can find that tutorial here: How To Test The Ford Mass Air Flow (MAF) Sensor.
Can I Drive My Pickup With A Bad MAF Sensor?
Depending on the the severity of the symptoms the bad MAF sensor is causing, you may not be able to safely drive the vehicle.
Even if it's possible to drive your car (with a bad mass air flow sensor), you should avoid doing so.
More Ford F150, F250, F350 Tutorials
You can find more Ford F150, F250, and F350 tutorials in the following index:
Here's a sample of the tutorials you'll find in the index:
- How To Test The Ford Ignition Control Module (Distributor Mounted).
- How To Test The Ford Ignition Control Module.
- Throttle Position Sensor (TPS) Test (Ford 5.0L, 5.8L).
- How To Test The Ford Mass Air Flow (MAF) Sensor.
If this info really saved the day, buy me a beer!