I am adding a heated O2 sensor to my car and am curious how to wire it. 3 pin connector. a and b are both white wires c is a black wire. how should they be properly hooked up?

 

Black- data to old O2 wire
white-12v switched (ignition or something else)
white-ground

-doesn't matter on the whites, just make sure one is switched 12v pos and one is ground.

 

oh, I remember having to look it up when I threw one in mine, and it had the same ambiguous wiring with it...
Right, so the 2 white wires are power and ground for the heater coil. The black wire is what you'd measure.

So usually you'd hook up a switched power source to a white wire, the other white wire would go to a ground source nearby, and also to the negative on your gauge or multimeter, and the black would be the positive on the gauge or multimeter.

 

I am electing to go 3-wire sensor myself.

I guess I dont understnad why they didn't just go with 2 wires instead of 3, since the body of the sensor is a ground to the manifold. (and a big ground at that). I would think big enough so as not to interfere with the readings of the sensor element itself. anyhoo...

Anyone know what the amp draw on the heater element is. I am contemplating where to splice in for the switch 12V source.

 

stumbled on this today. this is link is to an O2 sensor maker's catalog in Brasil and they list an O2 sensor as needing a 7.5 amp fuse http://www.thomson-net.com.br/arquiv...sor_Lambda.pdf

it'd be cool to have this from Bosch but this is as close as I found: Some of the other interesting facts from their catalog:

- FREQUENCY

- INITIAL WORKING TEMPERATURE

300

- INPUT VOLTAGE OF THE HEATER

- OHMIC VALUE OF THE HEATER

- HEATER FUSE

- THREAD

- HEXAGONAL

- TORQUE

- 03 Wires -

Output signal (black wire), two wires to power the heater (white wires) and the negative is made by the Sensor thread attached to the exhaust system.

- Ideal air/fuel ratio:

• Gasoline – 14.7:1

(14.7 parts of air for 01 part of gasoline)

• Alcohol – 9.0:1

(9.0 parts of air for 01 part of alcohol)

• Diesel – 15.2:1

(15.2 parts of air for 01 parts of diesel)

 

Typical heater draws about 4 - 6 Amp when cold and drops once NBO is up to operating temperature. The reason for three wires is that exhaust system is notoriously resistive - due to corrosion, bad ground return. You can improve over three wire (AFS-74) by going to four wire NBO (AFS-75). In four wire system extra wire is used to provide return path for signal wire back to ECM. However, some calibrations take into account extra ground losses by lowering stoich voltage from 450mv down. This can be easily changed in EPROM.

//RF

 

Life could be a little easier if you wire a 3-wire weather pack plug to your engine harness in place of the single wire plug. Wire it in, then plug your sensor into it.

http://www.partsamerica.com/productd...goryCode=4074E