TEST 4: Checking The Continuity Between The O2 Sensor And PCM

P0130, P0150 Front O2 Sensor Tests (1996-2000 3.3L Nissan Pathfinder)

The last battery of tests is to make sure that the wire that connects to terminal number 2 of the right (or left) upstream oxygen sensor isn't shorted to Ground or is ‘open’ somewhere between the sensor's harness connector and the PCM's connector.

This can easily be accomplished by doing a continuity test between the right (or left) upstream O2 sensor engine harness connector and the PCM harness connector and a continuity test between terminal number 2 and Ground.

NOTE: The left upstream oxygen sensor terminal number 2 wire connects to pin number 51 of the PCM connector. The right upstream oxygen sensor terminal number 2 wire connects to pin number 50 of the PCM connector.

These are the step tests:

  1. 1

    Disconnect the battery's negative terminal and:

    Disconnect the upstream oxygen sensor (that you need to test) from its engine harness connector.

    Disconnect the PCM from its harness connector.

  2. 2

    Testing the right upstream O2 sensor, test continuity between:

    Terminal number 2 of the O2's engine harness connector and terminal 50 of the PCM's harness connector.

    Continuity should exist.

  3. 3

    Testing the left upstream O2 sensor, test continuity between:

    Terminal number 2 of the O2's engine harness connector and terminal 51 of the PCM's harness connector.

    Continuity should exist.

  4. 4

    Test the continuity between:

    Terminal number 2 and engine Ground.

    Continuity should NOT exist.

    NOTE: This test applies to both the right or left upstream oxygen sensor.

Let's take a look at what your test results mean:

CASE 1: All of the continuity tests showed no problems. This test result tells you that that are no ‘opens’ or shorts to Ground in the circuit between the PCM's harness and the O2 sensor' harness connector.

Since you've reached this point because you have:

  1. Confirmed that the right (or left) upstream O2 sensor is stuck producing a continuous voltage in TEST 1.
  2. Confirmed that the right (or left) upstream O2 sensor does NOT react to a manually induced rich condition TEST 2.
  3. Confirmed that the heater element of the right (or left) upstream O2 sensor is within specification in TEST 3.

Tanking these test results into account, you can correctly assume that the upstream O2 sensor you're testing is fried and needs to be replaced with a new one.

CASE 2: One or several of the continuity tests showed a problem. Check all of your connections and repeat a test one more time.

If the continuity tests confirm the problem then repair the short to Ground or the ‘open’ in the circuit. Repairing this issue will solve the right or left upstream O2 sensor diagnostic trouble code (P0130 or P0150) lighting up the check engine light on your Nissan Pathfinder.

More Nissan Pathfinder Test Tutorials

You can find a complete list of tutorials here: Nissan 3.3L Index Of Articles.

Below is a small sample of the tutorials you'll find in the index:

  1. How To Test The Idle Switch (Nissan 3.3L Pathfinder, Xterra, Frontier).
  2. Throttle Position Sensor Test (Nissan 3.3L Pathfinder, Xterra, Frontier).
  3. How To Troubleshoot A No Start (Nissan 3.0L, 3.3L, 3.5L).
  4. How To Test The Starter Motor (Nissan 3.0L, 3.3L).
  5. How To Test Engine Compression (Nissan 3.0L, 3.3L, 3.5L).
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Infinite Vehicles:
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    • 1996, 1997, 1998, 1999, 2000