How To Test The MAF Sensor (1995-1997 2.3L Ford Ranger)

Sooner or later the mass air flow (MAF) sensor will fail on your 1995-1997 2.3L Ford Ranger.

The cool thing is that testing the MAF sensor isn't difficult, nor does it require expensive diagnostic equipment to test.

You can easily test the MAF sensor with a multimeter and in this tutorial, I'll walk you through the testing process.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAF (1995-1997 2.3L Ford Ranger) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.3L Ford Ranger: 1995, 1996, 1997.
• 2.3L Mazda B2300: 1995.

NOTE: The following tutorials will help you test the MAF sensor on the 1990-1994 2.3L Ford Ranger:

• How To Test The MAF Sensor (1990-1992 2.3L Ford Ranger).
• How To Test The MAF Sensor (1993-1994 2.3L Ford Ranger).

Symptoms Of A Bad MAF Sensor

As you probably already know, the MAF sensor is the component that tells the fuel injection computer how much air is entering the engine.

With the air flow measurement, the computer can now inject the right amount of fuel into the engine.

If the mass air flow sensor fails, the check engine light will illuminate with one of the following MAF sensor diagnostic trouble codes:

OBD I:

• Code 26: MAF Out Of Self-Test Range.
• Code 56: MAF Circuit Above Maximum Voltage.
• Code 66: MAF Circuit Below Minimum Voltage.
• Code 157: MAF Circuit Below Minimum Voltage.
• Code 158: MAF Circuit Above Maximum Voltage.
• Code 159: MAF Out Of Self-Test Range.

OBD II:

• 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.

A bad MAF sensor can cause quite a few engine performance issues. The following list, although not exhaustive, includes the most common symptoms you'll see:

• 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

In order to correctly diagnose the MAF sensor as good or bad, we need to know what each of the four wires coming out of the connector is doing.

The following table provides a brief description of each wire:

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

The MAF sensor requires 12 Volts to function. These 12 Volts are fed to the sensor via the red (RED) wire of the MAF sensor 4-wire connector.

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

We'll run a simple multimeter voltage test to verify that the RED wire is powering the MAF sensor with 12 Volts.

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 is labeled with the letter A in the photo 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. Double check all your multimeter connections and test again.

If you still don't see 12 Volts, you can conclude that the MAF sensor itself is not at fault as it will not function without 12 Volts.