How To Test The MAF Sensor (1993-1994 2.3L Ford Ranger)

The MAF sensor on your 1994-1995 2.3L Ford Ranger can be tested with a multimeter, no scan tool required,

This tutorial explains the four tests that will help you diagnose the MAF sensor as good or bad.

You can find this tutorial in Spanish here: Cómo Probar El Sensor MAF (1993-1994 2.3L Ford Ranger) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• 2.3L Ford Ranger: 1993, 1994.
• 2.3L Mazda B2300: 1994.

NOTE: The following tutorials will help you test the MAF sensor on the 1990-1992 and 1995-1997 2.3L Ford Ranger:

• How To Test The MAF Sensor (1990-1992 2.3L Ford Ranger).
• How To Test The MAF Sensor (1995-1997 2.3L Ford Ranger).

Symptoms Of A Bad MAF Sensor

When the MAF sensor fails, the fuel injection computer will register one of the following trouble codes:

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

A bad MAF sensor can cause quite a few engine performance issues. The following list, although not exhaustive, lists 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

The MAF sensor connector has four wires. Each wire of the connector has a specific job to do.

Here's the description of each circuit:

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

We'll start the MAF sensor diagnostic by checking that it is getting 12 Volts DC.

The red (RED) wire of the 4-wire connector supplies this voltage to the MAF sensor.

The RED wire connects to the terminal labeled with the letter A in the illustration above.

A simple voltage test will let us know if the RED wire is powering the MAF sensor or not.

NOTE: Testing the terminal from the front of the connector is not possible with multimeter test leads. To perform this test, you'll need to use a back probe on the connector or a wire piercing probe on the wire. You can see an example of this tool here: Wire Piercing Probe Review (Power Probe PWPPPPP01).

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. Recheck all of your multimeter connections and retest.

If you still do not see these 12 Volts, then this exonerates the MAF sensor as bad since without this voltage it will not function.