Guys My Supra has a three wire o2 sensor it's the one that was on the car when I bought it. But when I go to the parts store they only have the 1 wire can I still use it? and is the 3 wire stock?
O2 sensor 3 wire or 1 wire?
- Thread starter mk3supreme
- Start date
3 wire is for the heater.
Dunno for sure but it might chuck a code until it warms up if you use a single wire one.
Dunno for sure but it might chuck a code until it warms up if you use a single wire one.
I'd be curious to see if it made much of a difference, the computer doesn't use the NB o2 input when the engine is cold anyway does it?
Computer will whine and complain if you try to use a single wire sensor. Get a 3 wire - even if you have to splice it into the wiring harness manually.
Last I checked, MDCMotorsports on here had a shitload of stock O2 sensors for sale pretty damn cheap.
Last I checked, MDCMotorsports on here had a shitload of stock O2 sensors for sale pretty damn cheap.
Followup post - I've heard that the computer doesn't care about the other two wires, and I've heard that it does. Chances are I'm going to test both scenarios soon, and I'll let you know the results.
Grim thanks for the plug..... yes I have them in stock... they are genuine OEM denso o2 sensors, just need your old o2 sensor's plug.
I would only use 3 or 4 wire O2 sensors. 1 wire is OLD SCHOOL. you NEED/WANT the heater. Especially if the car has it stock. I got a 4 wire NTK sensor new off Ebay for like $25 shipped. My old 80's Corvette has a 1 wire Peice on it... I upgraded to a 4 wire and it was much better.
The reason I'm researching this is because I'm replacing the stock O2 with a wideband, and the output from the wideband to the ECU is only a single wire.
So, the question then is, do we just leave the heater wires disconnected, or do we need to wire in a resistor, or do we need to do something else?
So, the question then is, do we just leave the heater wires disconnected, or do we need to wire in a resistor, or do we need to do something else?
Ok Grim, I suppose one more won't hurt.
Th ecu controls the O2 sensor heater but does not monitor it. No code will be set if the heater become open although the sensor will become sluggish and will fall out of closed loop at idle and take longer to warm when cold.
Th ecu controls the O2 sensor heater but does not monitor it. No code will be set if the heater become open although the sensor will become sluggish and will fall out of closed loop at idle and take longer to warm when cold.
Last edited:
JJ, you are the whole reason I'm going to try it this way - before I read some of your posts on this subject, I was under the impression that the ECU monitored the heater circuit! 
I'm not concerned about falling out of closed loop, as I'll be feeding the signal from a wideband whenever the heater circut isn't hooked up - when I have the wideband out of the car, the heater circut will be plugged into a stock O2 sensor as normal.
I'm not concerned about falling out of closed loop, as I'll be feeding the signal from a wideband whenever the heater circut isn't hooked up - when I have the wideband out of the car, the heater circut will be plugged into a stock O2 sensor as normal.
Keep in mind what I'm telling you applies to what I know of the 87-88 ecus. I'm not certain if monitoring is done in the later computers but fwiw my TCCS books don't mention it. As far as I know heater power is simply supplied via the EFI Main Relay and the ecu provides a full time ground path for the heater after engine start.
I can tell you for sure that on my 87T sensor heater voltage remains fairly constant (although current varies as heater resistance changes) and an open in the heater circuit will not set any codes. Nor am I aware of any TCCS OBD-I codes related to heater failure. It's common with OBD-II however.
I can tell you for sure that on my 87T sensor heater voltage remains fairly constant (although current varies as heater resistance changes) and an open in the heater circuit will not set any codes. Nor am I aware of any TCCS OBD-I codes related to heater failure. It's common with OBD-II however.
suprarcr89
The Juggernaut has my old
1 wire n/a
3 wire turbo
id put the 3 wire on it. i bought one on here from mdc 3 wire worked great
3 wire turbo
id put the 3 wire on it. i bought one on here from mdc 3 wire worked great
Update!
I have discovered that the later ECUs must be slightly different. I wired in my ZT2 wideband, and used the narrowband sim output to drive the stock ECU's O2 sensor input.
I left the heater element leads from the original O2 plug disconnected. The ECU promptly threw a code 21, O2 sensor dying.
So, I wired in a 1000 ohm resistor across the leads for the heater... and the code went away instantly.
I have discovered that the later ECUs must be slightly different. I wired in my ZT2 wideband, and used the narrowband sim output to drive the stock ECU's O2 sensor input.
I left the heater element leads from the original O2 plug disconnected. The ECU promptly threw a code 21, O2 sensor dying.
So, I wired in a 1000 ohm resistor across the leads for the heater... and the code went away instantly.