Oxygen Sensor Heater Test -P0135 (1996-1997 2.4L Nissan Pickup)

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 10 to 12 Volts. The next and last step is to check the O2 sensor 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:

1. 1

   Place your multimeter in Ohms mode.

2. 2

   Connect the red multimeter test lead to the male terminal labeled with the number 1 in the illustration above.
   
   NOTE: This test is done on the connector of the O2 sensor itself. This connector has male spade terminals.

3. 3

   Connect the black multimeter test lead to the male terminal labeled with the number 3.

4. 4

   Your multimeter should register 2.3 to 4.3 Ω.
   
   If the heater element is fried, your multimeter will show an open (usually indicated by the letters OL) or a number over 10 K Ω.

Let's take a look at your test results:

CASE 1: The front O2 sensor's heater resistance is within specification. This is the correct test result and it 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 10 to 12 Volts (TEST 1).
•      -AND-
• 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.

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 Camshaft Position 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).