Diagnosing the rear oxygen sensor (HO2S 1/2) and/or diagnostic trouble code (DTC) P0141: 1/2 O2 Heater Failure is not as hard as you might think. You don't need any expensive diagnostic test equipment... all you'll need is a multimeter.
A trouble code P0141 tells you that the internal heater for the rear oxygen sensor has a problem. This usually happens when the heater (inside the rear O2 sensor) goes bad.
The cool thing is that the O2 sensor can be tested to be sure the heater element is fried. I'll show you the 3 basic tests you'll need to perform to find out.
NOTE: This oxygen sensor is known by several different names:
- Rear Heated Oxygen (O2) Sensor.
- HO2S 1/2.
- Downstream Oxygen (O2) Sensor.
- Oxygen Sensor Bank 1 Sensor 2.
Here are the contents of this tutorial:
- Circuit Descriptions of the Upstream Oxygen Sensor.
- TEST 1: Verifying the Heater Element is Getting Power.
- TEST 2: Verifying the Heater Element is Getting Ground.
- TEST 3: Testing the Heater Element's Resistance.
- Location Of The Oxygen Sensors.
- Where to Buy the Oxygen Sensor and Save Some $$$.
- More 4.7L Dodge Diagnostic Tutorials.
If you need to troubleshoot the front O2 sensor (HO2S 11), take a look at the following tutorial:
Puedes encontrar este tutorial en Español aquí: Calentador del Sensor de Oxígeno -P0141 (2000 4.7L Dakota, Durango) (en: autotecnico-online.com).
Circuit Descriptions of
the Upstream Oxygen Sensor
To be able to properly diagnose the rear O2 sensor's internal heater's issue and thus solve the P0141 trouble code, we need to know what each of the 4 wires of the sensor does.
Below, you'll find a description of the color of the wire and what type of signal it carries. We'll be using these circuit descriptions in this tutorial.
O2 SENSOR LOCATION: You can find the location of the rear oxygen sensor (HO2S 1/2) here: Location Of The Oxygen Sensors.
Below, you'll find the color of the wires of the engine wiring harness oxygen sensor connector for sensor HO2S 12:
|Downstream Oxygen Sensor (HO2S 12) Pinout
(2000 4.7L Dakota -Durango w/ Federal Emissions)
|1||ORG/DK GRN (or DK GRN/RED)||Heater Power (+)|
|2||BLK||Heater Ground (-)|
|3||BLK/LT BLU||O2 Signal Ground|
TEST 1: Verifying the Heater Element is Getting Power
To get this show on the road, we'll start by checking the basics... and this means making sure that the rear O2 sensor's heater is getting power and ground.
In this test section we'll check for power which is the form of 12 Volts DC.
The orange with dark green stripe (ORG/DK GRN) wire, of the rear O2 sensor's engine wiring harness connector, is the one that feeds power to the rear O2's heater element.
CAUTION: The O2 sensor gets and stays very hot even after the engine is off! Perform this and the following 2 tests with a completely cold engine. Be careful and take all necessary safety precautions!
IMPORTANT: The pinout in the illustration above is of the connector on the oxygen sensor itself. To check for 12 Volts, you need to test the ORG/DK GRN wire of the engine wiring harness sensor connector.
OK, this is what you'll need to do:
Locate the downstream oxygen sensor and disconnect it from its harness connector.
Locate the ORG/DK GRN wire of the engine wiring harness oxygen sensor connector.
With your multimeter in Volts DC mode, probe the RED with the red multimeter lead.
Ground the black multimeter lead directly on the battery's negative terminal.
With the Key On Engine Off (KOEO), the ORG/DK GRN wire should have 10 to 12 Volts DC.
Let's take a look at your test results:
CASE 1: The ORG/DK GRN wire has 10 to 12 Volts DC- So far so good since this test result confirms that the downstream oxygen sensor's heater element is getting power.
The next step is to make check that the BLK wire, of the O2 sensor engine wiring 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 ORG/DK GRN 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 downstream 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.