TEST 4: Checking The O2 Heater Element's Resistance
Alright, so far you have checked and confirmed that the O2 sensor's heater element is getting both power and Ground.
The very last thing we now need to do, is to check to see if the heater element (inside the oxygen sensor for Bank 1 Sensor 2) is fried or not.
This is a very simple and easy test that you can accomplish with your multimeter in Ohms mode.
NOTE: You'll be testing the circuits of the connector of the O2 sensor itself and not the O2 sensor harness connector (that's part of the engine wiring harness).
OK, this is what you need to do:
- Disconnect the oxygen sensor from the engine wiring harness connector (if it isn't already from the previous tests).
- Locate the O2 sensor wires that correspond to:
- The circuit C.
- The circuit D.
- Both of these letters should be embossed on the O2 sensor's connector to aid you in further identifying the circuits you need to test.
- With your multimeter in Ohms mode, check the resistance of this circuit.
- NOTE: Remember, you're testing the oxygen sensor itself.
- If all is OK, you should see about 4.5 Ω (Ohms).
- If the heater element is fried, your multimeter will show an open (usually indicated by the letters OL).
Let's take a look at your test results:
CASE 1: Your multimeter showed the indicated resistance. This tells you that you that the heater element within the oxygen sensor is OK.
CASE 2: Your multimeter DID NOT show the indicated resistance. This tells you that you that the heater element is fried. The oxygen sensor needs to be replaced.
If this info saved the day, buy me a beer!