Does anyone know which wire is for the heater on an oxygen sendor in a '95 civic dx 4 door Japanese built car? My Haynes manual says that it should be black, but I seem to have a yellow/black, green/white, red and white wire. How would I go about determining which it is? Thanks,

Andrew

 

I think on the harness it is:
yellow / black : heater power
red : heater return
green / white : sensor ground
white: sensor output

On the sensor, the two wires that are the same color (black or white) are the heater, and the sensor output is usually white, though it may be black if the heater wires are white.

 

Thanks mk. So how do I check to see if voltage is coming through the harness for the heater? I am not very savy with voltmeters or measuring currents, so i could use some guidance. Do I use the DC current settings (at say 20) and put the positive probe on the yellow/black and the negative to ground somewhere on the engine block? I appreciate the help,

Andrew

 

First unplug the sensor and measure resistance (the ohm symbol) between its two heater wires. It should be less than 50 ohms. If open circuit (the 1 keeps flashing like the leads aren't connected to anything), the sensor is bad. If that's OK set the meter to volts (20 volts if you have a choice) and measure like you said with the key on. The voltage should be about 12 volts.

 

Thanks again for your concise and easy to interpret answers mk378. I will give this a go shortly.

Andrew