How To Test The MAF Sensor (1998-2001 3.0L V6 Ford Ranger)

The mass air flow (MAF) sensor on the 1998-2001 3.0L V6 Ford Ranger can be tested without a scan tool.

In this tutorial, I'll explain how to test it with a multimeter. With four basic tests, you'll quickly determine if the MAF sensor is good or bad.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAF (1998-2001 3.0L V6 Ford Ranger) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 3.0L Ford Ranger: 1998, 1999, 2000, 2001.
• 3.0L Mazda B3000: 1998, 1999, 2000, 2001.

NOTE: The following tutorials will help you test the MAF sensor on the 1990-1997 3.0L Ford Ranger:

• How To Test The MAF Sensor (1990-1994 3.0L V6 Ford Ranger).
• How To Test The MAF Sensor (1995-1997 3.0L V6 Ford Ranger).

Symptoms Of A Bad MAF Sensor

The MAF sensor is a critical component of your Ford Rangers engine management system.

It is the component that measures the amount of air entering the engine which the fuel injection computer uses to inject the correct amount of fuel into the engines six cylinders.

When the MAF sensor fails, the fuel injection computer will illuminate the check engine light and register one of the following diagnostic trouble codes:

• P0102: MAF Signal Low Input to PCM.
• P0103: MAF Signal High Input to PCM.
• P1100: MAF Circuit Intermittent Voltage Input.
• P1101: MAF Sensor Circuit Output Voltage low During KOEO Self Test.

Not only will you see the check engine light illuminated on your Ford Ranger's instrument panel, you'll see one or more of the following engine performance issues:

• MAF sensor malfunction that DOES NOT light up the check engine light (CEL).
• Lean or rich air-fuel mixture diagnostic trouble code.
• Fuel trim diagnostic trouble code.
• Lack of power when accelerating the engine under load.
• Black smoke coming from the tail-pipe.
• Bad gas mileage.
• Engine idles rough and stalls.

MAF Sensor Circuit Descriptions

To successfully diagnose the MAF sensor as good or bad, we'll need to know what each of the four wires that stick out of the connector do.

The following table has a brief description of what each wire does:

Terminal	Wire	Description
D	Light blue with red stripe (LT BLU/RED)	MAF Signal
C	Tan with light blue stripe (TAN/LT BLU)	Ground (provided by PCM)
B	Black with white stripe (BLK/WHT)	Chassis Ground
A	Red (RED)	12 Volts

TEST 1: Making Sure The MAF Sensor Is Getting Power

To start our MAF sensor diagnostic, we'll check that the red (RED) wire of the MAF sensor connector is supplying 10 to 12 Volts DC.

In the photo above, I've labeled the RED wire with the letter A.

If the RED wire is supplying 10 to 12 Volts to the MAF sensor, our next step is to check that it's getting chassis Ground in TEST 2.

NOTE: Probing the front of the female terminal with your multimeter test lead can be a challenge. Be careful not to damage the terminal or you'll need to replace the connector.

These are the test steps:

1. 1

   Disconnect the MAF sensor from its electrical connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

   Connect the red multimeter test lead to the RED wire of the MAF sensor connector.
   
   The RED wire connects to the terminal labeled with the letter A in the illustration above.

4. 4

   Connect the black multimeter test lead probe the battery negative (-) terminal.

5. 5

   Turn the key ON but don't crank or start the engine.

6. 6

   You should see 10 to 12 Volts on the multimeter.

Let's interpret your test result:

CASE 1: The RED wire is supplying 10 to 12 Volts. This is the correct result.

The next step is to make sure the MAF sensor has Ground, for this, go to: TEST 2: Making Sure The MAF Sensor Is Getting Chassis Ground.

CASE 2: The RED wire IS NOT supplying 10 to 12 Volts. Without this voltage the MAF sensor will not function.

The most common cause of these missing 12 Volts is an open-circuit problem in the RED wire. Your next step is to find out why this voltage is missing and restore it back to the RED wire.