Oxygen Sensor Heater Test -P0141 (2000 4.7L Dodge Dakota, Durango)

TEST 2: Verifying The Heater Element Is Getting Ground

After having verified/confirmed that the rear O2 sensor's heater is being fed power by the ORG/DK GRN wire, the next step is to check that it's getting Ground.

The rear oxygen sensor's heater element is fed Ground by the black BLK wire (of the engine wiring harness rear O2 sensor's electrical connector).

We can do a very simple multimeter voltage test to see if Ground is indeed present or not.

IMPORTANT: The pinout in the illustration above is of the connector on the oxygen sensor itself. To check for Ground, you need to test the BLK wire of the engine wiring harness sensor connector.

These are the test steps:

1. 1

   Locate the BLK wire of the O2 sensor's engine wiring harness connector.
   
   NOTE: Remember, you'll test the wire that's on the engine wiring harness connector side and NOT on the O2 sensor itself.

2. 2

   Place your multimeter in Volts DC mode and connect the red multimeter test lead to battery (+).
   
   With the black multimeter test lead, probe the BLK wire of the O2 sensor's harness connector.

3. 3

   With the Key On, engine Off, this wire should have 10 to 12 Volts DC.

Let's take a look at your test results:

CASE 1: The BLK wire is feeding Ground since it registered 10 to 12 Volts DC. This confirms that the rear O2 sensor's heater has Ground.

Your next, and last, step is to check the heater element's resistance with your multimeter. For this test, go to: TEST 3: Testing The Heater Element's Resistance.

CASE 2: The BLK wire IS NOT feeding Ground since it DID NOT register 10 to 12 Volts DC. Double check that you're testing the correct wire and retest.

If you still don't get 10 to 12 Volts DC to register on your multimeter, then the most likely cause of this missing Ground is an 'open' in the BLK wire between the O2 sensor's harness connector and chassis Ground.

TEST 3: Testing The Heater Element's Resistance

Your rear O2 sensor diagnostic test results have shown that:

• A P0141 trouble code is lighting up the check engine light.
• The ORG/DK GRN wire, of the engine harness connector, is feeding the rear O2 sensor's heater with power (TEST 1).
• The BLK wire is feeding Ground to the rear O2 sensor's heater (TEST 2).

For our last test, we'll check that the heater element's resistance is within the factory specification. If it isn't, then we can conclude that the rear O2 sensor is bad and the cause of the P0141: 1/2 O2 Heater Failure trouble code.

NOTE: Just a reminder that the downstream 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

   Locate the rear O2 sensor terminals number 1 and number 2 of the rear O2 sensor connector itself (not the engine wiring harness O2 connector).

2. 2

   With your multimeter in Ohms mode, probe terminals number 1 and number 2 of the O2 sensor itself.

3. 3

   If all is OK, you should see about 3 to 30 Ωs on your multimeter.
   
   If the heater element is fried, your multimeter will show an open (usually indicated by the letters OL) or a number over 10 K Ωs.

Let's take a look at your test results:

CASE 1: Your multimeter confirmed the indicated resistance. This test result tells you that rear O2's heater is OK.

CASE 2: Your multimeter showed an open circuit (OL). This confirms that the rear O2 sensor's heater element is fried. Replacing the downstream O2 sensor with a new one will solve the P0141 trouble code lighting up the check engine light (CEL).

Here are some more specifics: Since you have:

• Confirmed that the rear O2 sensor's heater element is getting power (TEST 1).
•      -AND-
• Confirmed that the rear O2 sensor's heater element is getting Ground (TEST 2).
•      -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 downstream O2 sensor needs to be replaced with a new one.

Location Of The Oxygen Sensors

NOTE: The above illustration is for the 2000 4.7L Federal emissions equipped Dodge Durango / Dakota. These vehicles come equipped with 2 oxygen sensors instead of 4.

More 4.7L Dodge Diagnostic Tutorials

You can find a complete list of 4.7L Dodge tutorials in these two indexes:

• Dodge 4.7L Index Of Articles.

Here's a small sample of the tutorials you'll find in the index:

• How To Test The MAP Sensor (2000-2001 4.7L Dakota, Durango).
• How To Test The Throttle Position Sensor (2000-2007 4.7L Dodge).
• How To Test The Fuel Injectors (Dodge, Jeep 4.7L V8) (at troubleshootmyvehicle.com).
• How To Test For A Blown Head Gasket (4.7L Chrysler, Dodge, Jeep) (at troubleshootmyvehicle.com).
• How To Test The COP Ignition Coils (Chrysler, Dodge, Jeep 4.7L) (at troubleshootmyvehicle.com).