This article will help you to diagnose the mass air flow (MAF) sensor on any 2000, 2001, 2002 Nissan Sentra (with a 1.8L engine) using only a multimeter.
This is a simple multimeter test that's done in Volts DC mode. No Scan Tool's required or any other expensive testing equipment.
To help you navigate this article a little easier, here are its contents at a glance:
- Important Tips And Suggestions.
- How Does The MAF Sensor Work?
- MAF SENSOR TEST 1: Verifying The MAF Sensor Is Getting Power.
- MAF SENSOR TEST 2: Verifying The MAF Sensor Is Getting Ground.
- MAF SENSOR TEST 3: Verifying The 5 Volt Reference Voltage.
- MAF SENSOR TEST 4: Testing The MAF Signal Voltage.
Puedes encontrar este tutorial en Español aquí: Cómo Probar el Sensor MAF de 2000-2002 Nissan Sentra 1.8L (en: autotecnico-online.com).
Important Tips and Suggestions
TIP 1: The most effective way to test the MAF sensor on your Nissan Sentra is to test it while the engine is at normal operating Temperature and while it's running. Now, since you'll be working around a running engine, you'll need to be alert and take all safety precautions.
TIP 2:Three of four wires that come out of the mass air flow sensor connect directly to the Fuel Injection Computer... so you have to be very careful not to short these to 12 Volts, or you'll fry the computer.
TIP 3: You can use a digital or an analog multimeter. Both will work, although the Digital one is the preferred one due to its accuracy and rapid Signal responce.
How Does The MAF Sensor Work?
In a nutshell, this is how the mass air flow sensor works:
When you turn the Key to the On position and then start the engine, the MAF gets power thru' the wire labeled with the number 4. This power is in the form of 5 Volts.
Ground is provided by the Fuel Injection Computer thru' the circuit labeled with the number 3. The computer also provides a 5 Volt Reference Signal thru' the wire labeled with the number 2.
As the air enters the engine, the MAF sensor measures the amount of air flow and sends this info the Fuel Injection Computer.
So then, when you accelerate the engine, the Throttle Plate opens and the MAF sensor immediately measures the change in the amount of air entering and sends this info to the Fuel Injection Computer. This is accomplished thru' the wire labeled with the number 1.
Now, when you let go of the Accelerator Pedal, the Throttle closes and since the MAF is always sensing, it now sees the change in air flow and sends this new info to the computer.
The Fuel Injection Computer uses this info (that the MAF sensor provides) to control Fuel Injection, Ignition Advance and host of other things to keep your engine running smoothly.