You can test the mass air flow (MAF) sensor on your 1.6L Mazda Protegé without a scan tool. The multimeter mass air flow (MAF) sensor test in this tutorial is so accurate that you'll be able to say that the MAF sensor is bad and needs to be replaced or not.
Contents of this tutorial at a quick glance:
- Symptoms of a BAD MAF Sensor.
- What Tools Do I Need to Test the MAF Sensor?
- What Does the MAF Sensor Do?
- TEST 1: Checking the MAF Sensor Power Circuit.
- TEST 2: Checking the MAF Sensor Ground Circuit.
- TEST 3: Checking the MAF Sensor Signal.
- Where to Buy the MAF Sensor and Save.
The fuel injection computer, on your 1999-2001 1.6L Mazda Protegé, needs to know how much air is entering the engine. This and other engine operating information, it can inject the correct amount of gasoline.
Since the MAF sensor is such a critical component of your Protegé's engine management system, when it fails, you'll get the check engine light to shine nice and bright on your instrument cluster.
The failed MAF sensor will also caused one or several of the following symptoms:
- Diagnostic trouble codes:
- 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.
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: Abe's Multimeter Recommendation (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.
The MAF sensor is tasked with measuring the amount of air entering the engine at any given RPM. The PCM (Powertrain Control Module = Fuel Injection Computer) then uses this measurement of air flow to inject the correct amount of fuel.
To get into more specifics: The MAF sensor informs the PCM the amount of air flow entering the engine by converting the measurement of air into a voltage signal that increases with more air flow (as you accelerate the engine) or decreases as the engine breathes less air.
This is the key to understanding how to MAF sensor works and how to test it. I'll repeat it once more: The more air the engine breathes, the bigger the voltage signal the MAF sensor creates. The less air the engine breathes, the smaller the voltage signal the MAF sensor sends the PCM.
Here's what it looks like on a multimeter:
- At an idle under 1000 RPM's the MAF sensor outputs about 1.1 Volts DC.
- At about 1500 RPM's the math signal output is about 1.2 volts DC.
- Ask about 3000 RPM's the MAF signal output is about 1.7 volts DC.
Remember, the important thing to know, is that at higher RPMs, when the engine is breathing more air, the MAF signal (in voltage) is greater than when the engine is idling.
Now, in testing the MAF sensor, you won't be looking for a specific voltage number at a specific RPM... but for crazy fluctuations in the signal that don't correspond to the amount of air entering the engine or NO SIGNAL AT ALL.
These are the circuit descriptions of the mass air flow (MAF) sensor
|MAF Sensor Connector Pin Out|
|1||White w/ Red stripe||Fused power (12 Volts)|
|2||Black w/ White stripe||MAF sensor ground (PCM)|
|3||Green w/ Black stripe||MAF sensor signal|
|4||Blue w/ Black stripe||Intake Air Temp (IAT) Sensor|
|5||Brown||Intake Air Temp (IAT) Sensor|
As you’re probably already aware, the MAF sensor on your Mazda has 5 wires coming out of it’s connector. We only need to be concerned with three of the five wires... since the other 2 belong to the intake air temperature (IAT) sensor that is part of the MAF sensor assembly.
Let's turn the page and get testing...