TEST 2: Testing The Heater Element's Resistance
If you've reached this point, you've confirmed that the front O2 sensor's heater is being fed power and ground. The next and last step is to check the heater's internal resistance with your multimeter in Ohms mode.
NOTE: Just a reminder that the upstream oxygen sensor has to be completely cold before proceeding with this test since the manual calls for the O2 sensor to be at room temperature for the resistance test.
OK, this is what you need to do:
Locate the O2 sensor outer 2 terminals (1 and 3) of the O2 sensor connector itself (not the engine wiring harness O2 connector).
With your multimeter in Ohms mode, probe terminals 1 and 3 of the O2 sensor itself.
Remember, you'll probe the outer 2 terminals of the O2 sensor's connector (which are male spade terminals) and not the engine wiring harness connector (which has female terminals).
If all is OK, you should see about 3 to 1000 Ωs on your multimeter.
If the heater element is fried, your multimeter will show an open (usually indicated by the letters OL) or a number over 10 K Ωs.
Let's take a look at your test results:
CASE 1: The front O2 sensor's heater resistance is within spec.- This test result tells you that front oxygen sensor's heater is OK.
CASE 2: Your multimeter showed an open circuit (OL)- This confirms that the upstream O2 sensor's heater element is fried. Replacing the upstream O2 sensor with a new one will solve the P0135 trouble code lighting up the check engine light (CEL).
Here are some more specifics: Since you have:
- Confirmed that the front O2 sensor's heater element is getting power and ground (TEST 1).
- In this test you have confirmed that the heater element's resistance is out of specification.
Taking all of the above into account you can correctly conclude that the upstream O2 sensor needs to be replaced with a new one.
Where To Buy The Oxygen Sensor And Save Some $$$
The following links will help you to comparison shop for the front oxygen sensor on your 1996-1997 2.4L Nissan Pick Up.
NOTE: If you're not sure if the above upstream O2 sensor fits your particular Nissan Pick Up. Don't worry. Once you get to the site, they'll make sure the sensor switch is the correct one, if not, they'll find you the correct one.
More 2.4L Nissan Tutorials
You can find a complete list of tutorials in this index: Nissan 2.4L Index of Articles.
Here's a small sample of the 2.4L Nissan tutorials you'll find in the index:
- How To Test The Power Transistor 2.4L Nissan Frontier, Xterra (1998-2004).
- How To Test The Cam Sensor 2.4L Nissan Frontier, XTerra (1998-2004).
- Mass Air Flow (MAF) Sensor Test 2.4L Nissan D21 Hard Body (1990-1995).
- How To Test The Fuel Injectors (Nissan 2.4L) (at: troubleshootmyvehicle.com).
- How To Test Engine Compression (Nissan 2.4L) (at: troubleshootmyvehicle.com).
If this info really saved the day, buy me a beer!