Can a single wire oxygen sensor replace the 3 wire in my 95 Legacy? Will it work and worse without the heater? Just checking on my to do list before it gets cold.

 

Thanx,

Pete

A one wire, as you know, is a three wire, without the heater. Depending on the weather and the location of the sensor, it may or may not remain hot enough to function correctly. I doubt there is a way to know for sure.

 

My old Saab had a bad O2 sensor heater. I didn't know until I was driving in near zero degree weather. Whenever I stopped, the idle would hunt up and down, a pretty good sign that the O2 sensor is bad and yes, the heater circuit in the sensor was open (broken). Driving around in more normal temps 32F and above, I never experienced the idle speed hunting.

 

Unless you have a free 1 wire sensor to use, and cost is a big factor, I'd get the heated sensor.

 

Jack

oddly enough i run a heated o2 from a saab in my 85 subaru rx .. and it makes a lot of difference compared to a non heated unit

 

you can get "universal" heated o2's a bit cheaper

I read on the 'Net that an o2 sensor has to be HOT to work properly... Marty

correct !

but then again thats the reason why you would want a 3 wire heated o2

 

since it has a internal heating element that keeps it at the minimum temp

that is is designed to work at

instead of letting the exhasut gasses heat the unit up

 

so in factory 3 wire heated cars do indeed put in a 3 wire heated unit

in non 3 wire heated cars <older>

add a relay that is tripped off the coil + and supply power to the heating unit on the o2 and enjoy the benefits of a better running engine due to backyard mechanic engineering

Thanx guys - a 3 wire it is!!!

oddcomp,

 

I would like to try adding a heated O2 sensor to my XT6. Could you please elaborate on how to add a heated sensor to a car that originally came without one? The phrase "tripped off the coil +" is too general for a person like me. I can work with electricals, but I hate it so I don't ever do it and I don't really understand what you mean. If you could assist I'd really appreciate it. Thanks!

 

--Eoin

sending pm to you so as not to clutter up someone elses thread

 

but i can re pm or post openly for others

post openly here or xt6.net, i'll do the same on mine!

copy/paste PM's if you've already exchanged.

thanks for the heads up.

Could you please elaborate on how to add a heated sensor to a car that originally came without one?

 

Why are you doing this? A heated sensor is really only a benefit at startup (cold engine) and in exceptionally cold conditions. If the O2 sensor is relatively near to the engine, it should stay hot, once the engine is warm. I don’t think I’d ever retrofit a single wire to a three or four wire. I doubt there is much benefit.

 

If you really want to do it, just run one leg of the heater lead off the fuel pump circuit and the other to ground. The senosr will draw a few amps to start, then tail off to zero or near zero as the engine exhaust takes over and keeps the sensor hot.

 

Jack

sorry i fell aslep when posting my reply and the laptop shutdown oops

the way i did it was i took a relay jumped a wire off the + side of the coil to a relay <they usually have diagrams on them showing wich connections are for the relay magentic coil and wich connections are for the power contacts>

put a ground to the other side of the magnetic coil connectors

 

so when the ignition is turned on it should click over

 

next i ran one wire of the o2 heating element to ground and the other to the relay power switch contacts and then the other terminal went to the battery

i would suggest adding about a 5amp fuse inline from the battery to the relay some where

 

like stated above it only pulls a few amps to heat up

but unlike stated above often depending on location of the sensor at idle or even low speed driving it will cool down enough to the non working point

happens in my turbo suby that why i went to a heated unit

helped alot with the factory ecu before i ditched it

 

oh and that would be a few amps your ignition would not get and the coil output could suffer from it and make things worse