Oxygen Sensor Heater Test -P0141 (1.6L Suzuki Sidekick, Geo Tracker)

If a trouble code P0141 is lighting up the check engine light on your 1.6L Sidekick, this tutorial will help you diagnose it.

The diagnostic involves 3 basic tests and these are: making sure that the downstream oxygen sensor's heater element is getting power and ground. Finally, making sure the heater element's internal resistance is within specification.

Here are the contents of this tutorial:

  1. Circuit Descriptions of the Downstream Oxygen Sensor.
  2. TEST 1: Verifying Power and Ground to the Heater.
  3. TEST 2: Testing the Heater Element's Resistance.
  4. Where to Buy the Oxygen Sensor and Save Some $$$.
  5. More 1.6L Suzuki Tutorials.

NOTE: The 1996 thru' 1998 1.6L Suzuki Sidekick has 2 oxygen sensors. One before and one after the catalytic converter. If you need to test the front oxygen sensor's heater (or a P0135 trouble code) see this tutorial: Oxygen Sensor Heater Test -P0135 (1996-1998 1.6L Suzuki Sidekick).

Circuit Descriptions of
the Downstream Oxygen Sensor

Oxygen Sensor Heater Test -P0141 (1.6L Suzuki Sidekick, Geo Tracker)

The test for power and ground are done on the oxygen sensor's engine wiring harness connector. The resistance test is done on the oxygen sensor's connector itself.

Here are the specifics:

  1. The connector on the O2 sensor itself has male spade terminals.
  2. The engine wiring harness connector has female terminals.
  3. To check for power and ground, we'll test the engine wiring harness O2 connector.
  4. To test the O2 sensor heater's internal resistance we'll test the connector on the O2 sensor itself.

The illustration I'm using throughout this tutorial is the connector of the O2 sensor itself.

Here's a brief description of the 4 wires of the rear oxygen sensor:

Rear Oxygen Sensor Pinout
(1996-1998 1.6L Suzuki Sidekick)
Pin Wire Color Description
1 GRY/YEL (or BRN or ORG/WHT) O2 Signal Ground
2 RED/BLU (or YEL) -1996
YEL (or YEL/BLU) -1997, 1998
O2 Signal
3 PNK/WHT -1996
PNK/BLK -1997, 1998
Heater Power (-)
4 BLK/WHT Heater Power (+)

TEST 1: Verifying Power and Ground to the Heater

Oxygen Sensor Heater Test -P0141 (1.6L Suzuki Sidekick, Geo Tracker)

As you're probably already aware, the rear oxygen sensor's activates when it gets power (12 Volts) and ground. If any of these two are missing, the check engine light will illuminate with a P0141 trouble code.

So, the very first thing we'll do is make sure that both are present. The wires that supply these 2 are:

  1. The black with white stripe (BLK/WHT) wire is the one that supplies 12 Volts.
  2. The pink with white stripe (PNK/WHT) wire or pink with black stripe (PNK/BLK) wire is the one that supplies ground.

NOTE: This test is done on the oxygen sensor's engine wiring harness connector. This connector has female terminals.

OK, this is what you'll need to do:

  1. 1

    Verify that the black with white strip (BLK/WHT) wire has voltage (10 to 12 Volts DC ) with the key on but engine off.

    Connect the red multimeter test lead (using the appropriate tool) to the BLK/WHT wire. Connect the black multimeter test lead to the negative battery terminal.

    Your multimeter should read 10 to 12 Volts DC.

  2. 2

    Verify that the pink with white stripe (PNK/WHT) wire or pink with black stripe (PNK/BLK) wire has ground with the key on but engine off.

    Connect the black multimeter test lead (using the appropriate tool) to the ground wire. Connect the red multimeter test lead to the positive battery terminal.

    Your multimeter should read 10 to 12 Volts DC.

Let's take a look at your test results:

CASE 1: Your multimeter confirms that the heater is getting power and ground- This is the correct and expected test result.

For our last test, we need to verify that your 1.6L Suzuki Sidekick's O2 sensor heater's resistance is within specification. For this test, go to TEST 2: Testing the Heater Element's Resistance.

CASE 2: Your multimeter confirms that the heater IS NOT getting power and ground- The most likely cause is that power is missing due to a blown fuse or a short (or open) in the wiring. You'll need to check fuse #16 (10 amps) in the fuse box and make sure it's not blown.

If the fuse is OK, your next step is to find out why this battery power is missing using a wiring diagram.