How To Test The Rear O2 Heater -P0141 (1997-2000 2.2L Camry)

TEST 2: Testing The Heater Element's Resistance

In TEST 1, you confirmed that your 2.2L Camry's rear O2 sensor's heater element is getting power (12 Volts) and Ground, the next and last test is to check its internal resistance.

The resistance specification, for the rear O2 sensor's heater element is 11 to 16 Ohms (with the sensor at 68°F -20°C).

If the rear O2 sensor's heater element's resistance isn't within specifications, then you can conclude that it's bad and needs to be replaced.

We'll use our multimeter in Ohms mode to check for this resistance.

These are the tests steps:

1. 1

   Locate the O2 sensor terminals number 1 and number 2 of the 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 11 to 16 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: The multimeter confirms that the rear O2 heater's resistance is within factory specification. This test result tells you that the rear O2's heater is OK.

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

You can correctly conclude that your 2.2L Toyota Camry downstream O2 sensor needs to be replaced with a new one if you have:

1. Confirmed power and Ground is reaching the sensor's heater (TEST 1).
2.      -AND-
3. In this test you have confirmed that the heater element's resistance is out of specification.