TEST 2: Testing The Heater Element's Resistance

Testing The Heater Element's Resistance. Rear Oxygen Sensor Heater Test -P0141 (1996-1997 2.4L Nissan Pickup)

In this last test, you're gonna' make sure that the rear O2 sensor heater's resistance is within specification. This resistance spec is: 3 to 4 Ohms.

If the resistance spec IS NOT within factory specification and you've confirmed that the rear O2 heater is getting power, then you can conclude that the sensor's heater is fried and that it needs to be replaced!

NOTE: Just a reminder that the downstream 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:

  1. 1

    Using the illustration above, locate O2 sensor terminals 1 and 4 of the O2 sensor connector itself (not the engine wiring harness O2 connector).

  2. 2

    Place your multimeter in Ohms (Ω) mode.

  3. 3

    Probe terminals 1 and 4 of the O2 sensor itself.

    Remember, you'll probe the male terminals of the O2 sensor's connector and not the female terminals of the engine wiring harness connector.

  4. 4

    If all is OK, you should see about 3 to 4 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 rear O2 sensor's heater resistance is within specification. This test result tells you that rear oxygen sensor's heater is OK.

CASE 2: Your multimeter showed an open circuit (OL). This confirms that the downstream O2 sensor's heater element is fried. Replacing the downstream O2 sensor with a new one will solve the P0141 trouble code lighting up the check engine light (CEL).

To be a bit more specific, you can conclude that the rear O2 sensor needs to be replaced if you have:

  1. Confirmed that the rear O2 sensor's heater element is getting power (TEST 1).
  2.      -AND-
  3. Confirmed that the heater element's resistance is out of specification.

Where To Buy The Oxygen Sensor And Save Some $$$

The following links will help you to save some bucks on the rear oxygen sensor:

NOTE: If you're not sure if the above downstream O2 sensor fits your particular 2.4L Nissan Pickup, don't worry, once you get to the site, they'll make sure the sensor is the right one, if not, they'll find you the right 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:

  1. How To Test The Power Transistor 1992-1994 Nissan D21 Pickup.
  2. How To Test The Camshaft Position Sensor 2.4L Nissan Frontier, XTerra (1998-2004).
  3. Mass Air Flow (MAF) Sensor Test 2.4L Nissan D21 Hard Body (1990-1995).
  4. How To Test The Fuel Injectors (Nissan 2.4L) (at: troubleshootmyvehicle.com).
  5. How To Test Engine Compression (Nissan 2.4L) (at: troubleshootmyvehicle.com).
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