The mass air flow meter in your Nissan is also known as the Pathfinder MAF Sensor. This part is responsible for informing your engine computer of how much air is entering the engine. The Nissan Pathfinder MAF Sensor is a vital part of how your engine operates, and without a properly working mass air flow sensor, your 3.5 liter engine will run poorly.
Your Pathfinder MAF Sensor is a five pin unit that’s mounted to your MAF housing. This MAF housing is typically found bolted to your stock airbox. Today I’ll be showing you how to troubleshoot and test a mass air flow sensor in a 2001 Nissan Pathfinder. This Nissan truck is equipped with the 3.5 liter engine, and you’ll need to use a digital multimeter to complete this How To tutorial.
When your Nissan Mass Air Flow sensor isn’t working your engine computer or ECU will not know what is going on. This will cause your engine to either run rich meaning too much fuel, or too lean meaning not enough fuel.
Symptoms of a bad Pathfinder MAF Sensor
When your mass air flow sensor in your 3.5 liter Nissan goes out, you’re going to have several symptoms. Some of these symptoms are minor and can range from slightly troublesome to annoying. But most will be more serious and can lead to premature engine damage or catalytic converter failure.
- Engine misfire
- Check engine light ON
- Lean engine condition
- Rich engine condition – bad gas mileage
- Poor engine performance
If you have any of these problems in your Nissan Pathfinder, it’s time to check your MAF sensor. We will be starting our Pathfinder MAF Sensor tutorial with the power and ground signals.
How to Test your Pathfinder MAF Sensor for power
To begin we will be using our digital multimeter to check and make sure that the mass air flow sensor is getting power. The pin you will be checking is PIN A as shown in our Pathfinder MAF Sensor diagram below.
Gently touch the multimeter probe to PIN A on the ENGINE side of the MAF connector. With the key turned to the “ON” position, you should have 12 volts of DC power at this wire. If you have power here, you will then check PIN B on the ENGINE side of the wiring harness. This wire should be a low reference ground signal.
If you have both power and ground, that means your Pathfinder MAF Sensor is powering up. Now check PIN C on the wiring harness for a 5 volts of DC power. If these three wires check out with your multimeter, it’s time to move onto the signal wire.
Check your Pathfinder MAF Sensor Signal Wire
If your Nissan Pathfinder has a mass air flow sensor low signal or high signal OBDII check engine code, this part of the test is for you. If you have already tested for power and ground the last part of our Pathfinder MAF Sensor How To Guide will show you how to measure for the signal at PIN D.
You will need to reconnect the MAF sensor for this part of the test. Plug your wiring harness back into your mass air flow sensor.
This part of our tutorial is potentially dangerous, so make sure to keep your hands, clothing and tools clear of the engine, drive belts and especially the cooling fan. Now start your engine and allow it to warm up.
Now you will either use an unbent paper clip to backpin the fourth and last wire. Or you can use the multimeter to pierce the wire at PIN D. At idle the voltage being sent by your mass air flow sensor should be between 1.0 and 1.2 volts of signal.
You can either manually open your throttle or have a friend sit in the car. Make sure the transmission is in PARK or NEUTRAL, and increase the engine speed to 3000 RPM. At this RPM you should be reading between 2.5 and 2.7 volts of DC signal.
If you have completed this guide and the test results from your multimeter shows your Pathfinder MAF Sensor responding within this range, you are okay. Remember that the values may not be exact but they should be within this specified range. If your mass air flow sensor isn’t responding as you expect, it’s time to replace your Pathfinder mass air flow sensor.
You can then use a OBDII scan tool to clear your check engine code and clear your CEL light.
