Oxygen Sensor Heater Test -P0135 (1998-2000 2.5L Stratus/Cirrus)

A diagnostic trouble code P0135 can be easily diagnosed on your 1998, 1999, or 2000 2.5L V6 equipped Dodge Stratus or Chrysler Cirrus.

A trouble code P0135 refers to an upstream heater element problem... and with the help of this tutorial you'll be able to make sure the heater is getting: power, ground, and that it's resistance is within specification.

Here are the contents of this tutorial:

  1. Circuit Descriptions Of The Upstream Oxygen Sensor.
  2. TEST 1: Verifying The Heater Element Is Getting Power.
  3. TEST 2: Verifying The Heater Element Is Getting Ground.
  4. TEST 3: Testing The Heater Element's Resistance.
  5. Where To Buy The Oxygen Sensor and Save Some $$$.

The 1995 thru' 1997 2.5L Dodge Stratus (2.5L Chrysler Cirrus) uses a different oxygen sensor (the connector is squared). To test this upstream oxygen sensor, go here: Oxygen Sensor Heater Test -P0135 (1995-97 2.5L Stratus/Cirrus).

Circuit Descriptions Of The Upstream Oxygen Sensor

Oxygen Sensor Heater Test -P0135 (1998-2000 2.5L Stratus/Cirrus)

The upstream oxygen sensor is a 4 wire type. 2 wires are for the part of the sensor that monitors the oxygen content of the exhaust. The other 2 wires are the ones that feed power and ground to the O2 sensor's heater element.

Below, you'll find the color of the wires of the engine wiring harness oxygen sensor connector:

Upstream Oxygen Sensor Pinout
(1998-2000 2.5L Stratus, Cirrus)
Pin Wire Color Description
1 BLK/LT BLU Heater (-) Ground
2 BLK/DK GRN Heater (+) Power
3 DK GRN/ORG O2 Sensor Ground
4 BLK O2 Sensor Signal

TEST 1: Verifying The Heater Element Is Getting Power

Oxygen Sensor Heater Test -P0135 (1998-2000 2.5L Stratus/Cirrus)

We're gonna' start troubleshooting the P0135 trouble code by checking the basics. By this I mean making sure the oxygen sensor heater is getting power and ground.

In this test section we're gonna' make sure that the dark green with orange stripe (DK GRN/ORG) wire, of the upstream O2 sensor engine wiring harness connector, has battery voltage with the ignition key in the On position.

In TEST 2 we'll check that the O2 sensor heater is getting ground.

NOTE: The illustration above is of the connector on the oxygen sensor itself. To check for power to the heater element, you need to test the DK GRN/ORG wire of the engine wiring harness sensor connector.

IMPORTANT: The O2 sensor can get and stay very hot! Perform this test with a completely cold engine. Be careful and take all necessary safety precautions!

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

  1. 1

    Locate the upstream oxygen sensor and disconnect it from its harness connector.

  2. 2

    Locate the DK GRN/ORG wire of the engine wiring harness oxygen sensor connector.

  3. 3

    With your multimeter in Volts DC mode, probe the DK GRN/ORG with the red multimeter lead.

    Ground the black multimeter lead directly on the battery's negative terminal.

  4. 4

    With the Key On Engine Off (KOEO), the DK GRN/ORG wire should have 10 to 12 Volts DC.

Let's take a look at your test results:

CASE 1: Your multimeter confirms that the DK GRN/ORG wire has 10 to 12 Volts DC- So far so good since this test result confirms that the upstream oxygen sensor's heater element is getting power.

The next step is to make check that the BLK wire, of the O2 sensor harness connector, is feeding ground to the heater element. For this test, go to TEST 2: Verifying The Heater Element Is Getting Ground.

CASE 2: Your multimeter confirms that the DK GRN/ORG wire DOES NOT have 10 to 12 Volts DC- Re-check that you're testing the correct wire and that the Key is in the RUN position (but don't crank or start the engine) and re-test.

If you still don't see 10 to 12 Volts DC... then this test result tells you that the upstream oxygen (O2) sensor itself IS NOT BAD... since without power, the heater element won't work.

Although it's beyond the scope of this article... the next step is to find out why this battery power is missing using a wiring diagram.