In this tutorial I'm going to show you how to test the mass air flow (MAF) sensor using a multimeter.
You don't need a scan tool to test the mass air flow sensor on your 1996-1998 1.5L Mazda Protege.
All of the tests that are explained in a step-by-step manner so that you can easily find out if the MAF sensor is bad or not.
Contents of this tutorial:
- Symptoms Of A Bad MAF Sensor.
- What Tools Do I Need To Test The MAF Sensor?
- How Does The MAF Sensor Work?
- MAF Sensor Circuit Descriptions.
- TEST 1: Making Sure The MAF Sensor Is Getting 12 Volts.
- TEST 2: Making Sure The MAF Sensor Is Getting Ground.
- TEST 3: Checking The MAF Sensor Signal With A Multimeter.
- More 1.5L Mazda Protege Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Sensor MAF (1996-1998 1.5L Mazda Protege) (at: autotecnico-online.com).
APPLIES TO: This MAF sensor diagnostic tutorial applies to the following vehicles:
- 1996, 1997, 1998 1.5L Mazda Protege.
RELATED WIRING DIAGRAMS:
Symptoms Of A Bad MAF Sensor
The fuel injection computer, to be able to inject the correct amount of fuel into the engine, needs to know how much air is entering the engine.
And as you're probably already aware, it's the mass air flow sensor that is tasked with measuring the amount of air that enters the engine.
Since the MAF sensor is such a critical component of your Protege's engine management system, when it fails, you'll see one or several of the following symptoms:
- Diagnostic trouble codes lighting up the check engine light:
- P0101: Mass Air Flow (MAF) Sensor System Performance
- P0102: Mass Air Flow (MAF) Sensor Circuit Low Input.
- P0103: Mass Air Flow (MAF) Sensor Circuit High Input.
- Bad gas mileage.
- Rough idle.
- Lack of power on acceleration.
- Black smoke coming out of the tailpipe.
- Won't pass the emissions test.
It's rare for the mass air flow (MAF) sensor to go bad and not leave a diagnostic trouble code but sometimes you'll get the MAF trouble code and the MAF is good. So, it's always a good idea to test it.
What Tools Do I Need To Test The MAF Sensor?
The cool thing about testing the MAF sensor on your Mazda is that you don't need any expensive or exotic tools. Here's a basic list of tools you'll need:
- A multimeter.
- If you need to upgrade or buy a multimeter, check out my recommendation: Buying A Digital Multimeter For Automotive Diagnostic Testing (found at: easyautodiagnostics.com).
- Wire piercing probe.
- Although this tool is not an absolute must, if you do buy one, you'll realize just how easy it makes testing the voltages inside the wires.
- If you need to see what this tool looks like, you can see it here: Wire Piercing Probe.
A scan tool comes in handy but you won't need it to use the testing info in this article.
How Does The MAF Sensor Work?
As I mentioned earlier, the MAF sensor is tasked with measuring the amount of air entering the engine at any given RPM.
With this air flow measurement, the fuel injection computer can then inject the correct amount of fuel.
Specifically: The MAF sensor informs the PCM the amount of air flow entering the engine by converting the measurement of air into a voltage signal.
- This voltage signal increases as more air enters the engine.
- This voltage signal decreases as less air enters the engine.
The key to understanding how to MAF sensor works and how to test it is remembering that its voltage signal increases/decreases with more/less air flow.
MAF Sensor Circuit Descriptions
As you're probably already aware, the MAF sensor on your Mazda has 3 wires coming out of its connector.
These are their circuit descriptions:
|MAF Sensor Connector Pin Out|
|1||White With Red Stripe (WHT/RED)||12 Volts|
|2||Light Green With Black Stripe (LT GRN/BLK)||MAF Signal|
|3||Black With Light Green Stripe (BLK/LT GRN)||Ground|
The following MAF sensor wiring diagram may come in handy: MAF Sensor Circuit Wiring Diagram (1996-1998 1.5L Mazda Protege).
Let's turn the page and get testing.