The Camry Rear O2 Sensor in your Toyota can also be called the O2 sensor or air fuel monitor. The primary purpose of the Camry Oxygen Sensor is to determine how efficiently your engine is running. Mounted after your catalytic converter, this sensor analyzes your exhaust gases to ensure that your emissions equipment is working properly. By reading the exhaust gases the O2 sensor transmits its findings to your Toyota engine computer.
Your Toyota engine computer will trigger a Camry check engine light with a failed secondary or downstream oxygen sensor failure. Some of these common stored OBDII DTC trouble codes can include a P0420 code. The specific language behind this trouble code is Catalyst System Efficiency Below Threshold. If you aren’t sure what your Camry check engine light is for, use the right OBDII scan tool to check it.
When this happens your Camry check engine light will turn on, and your Toyota won’t pass emissions. Today I’ll be showing you how to test the Camry rear O2 sensor in a 2000 Toyota with a 2.2 liter engine in it. In order to check the function of your secondary or downstream oxygen sensor, you will need to use a digital multimeter.
If your Camry check engine light comes back related to your downstream O2 sensor, you’ll need to perform this test. You don’t want to buy a replacement secondary oxygen sensor only to find that your catalytic converter is to blame.
To do this you’ll need to jack up the passenger side of the vehicle. Always make sure that your transmission is in PARK or NEUTRAL, and that your parking brake is firmly engaged. Get under your Camry and unplug the downstream oxygen sensor. This is connected by way of a four pin weatherproof oxygen sensor connector.
We’ll begin the testing procedure by checking for power at the secondary O2 sensor. You will need to reference our Camry Rear O2 sensor wiring diagram below to continue.
Check the Camry Rear O2 Sensor for Power
The heater element is what you’ll be checking here. To do this turn the ignition in your Toyota Camry to the ON position. Now you will be checking the ENGINE harness side of the Toyota at the wire that leads to PIN B.
You should have a switched 12 volt power signal at this wire. The Camry Rear O2 sensor wire you are checking for power is a BLACK wire with a YELLOW stripe in it.
If you have 12 volts at this wire, the next wire to check is your ground circuit. This is located at the wire leading to PIN A, which is a PINK wire with a BLACK stripe in it.
There is one more wire to check for a ground circuit, and that’s the one that represents your Camry rear O2 sensor signal low reference wire. This is the wire that leads to PIN D and it’s a BROWN wire. If you have ground circuits at the PIN D as well as PIN A, and 12 volts at PIN B then your Camry Rear O2 Sensor should have everything it needs to function.
Clear your Camry check engine light using your scan tool and see if your trouble code returns. If it does then it’s time to check the downstream oxygen sensor directly and measure the internal resistance of the heater element.
Test the Camry Rear O2 Sensor Internal resistance
The heater element in your Camry Rear O2 sensor is a good way to gauge the functionality of this air fuel sensor. To do this access your downstream oxygen sensor harness, only this time you are checking at the sensor itself.
The pins on the Camry downstream oxygen sensor to test are PIN A and PIN B. Turn the dial of your multimeter to read OHMS Ω, and gently probe the SENSOR side of the secondary oxygen sensor.
You should read between 11 to 16 ohms Ω worth of resistance. If you see an open condition or a reading outside of this range, then your Camry Rear O2 sensor is fried.
If your Camry rear O2 sensor does not respond, it’s dead and must be replaced. This is the only way your Camry will pass smog. Remove the downstream O2 and install a replacement Camry oxygen sensor. Have any questions about our How To testing guide? Leave us a comment below and let us know!