1 wire O2 conversion

[Ryanpzz]

The original 4 wire Oxygen sensor for our cars is just too expensive in my opinion. I've been lookin around and the cheapest price I can find is $45 from ngk.com and that's for a universal 4-wire O2 sensor that I will have to splice into the connector from my old O2's. After shipping we're looking at >$100 to replace both of my bad oxygen sensors.

All oxygen sensors work the same way (with the exception of wide-band oxygen sensors). Only one wire is needed to provide the ECU with a signal. Our cars have 4 wire oxygen sensors. 1 wire provides the signal, 2 wires provide power for the heating element that allows the oxygen sensor to reach operating temperature faster, and the remaining wire is a ground just to make sure the sensor is grounded.

So eliminating the other three wires, it's possible to replace the 4 wire sensor with a cheap universal 1-wire sensor from autozone for $18 each. Just tap into the signal wire on your old oxygen sensor connector and remove the other three wires from the connector.

I know a lot of you probably won't like the idea, but I no longer get a check engine light, and I saved myself more than $60 .

[spada]

Ryan, I can't believe you posted in the 2.5 Forums. welcome keep the mad scientist ideas comin!

[pgt4speed]

I think I may try that.....

[taz42zero]

that's not a bad idea, hmmmmmmm. i think i may have to try that next time instead of spending $120 for 2 damn 02's.

[Jeff L]

So prior to engine warm-up, the performance is the same? Will that change in the winter?

Nice tip!

[Ryanpzz]

I have test wires ran inside the engine compartment... from a cold start the O2's start to respond within 30 seconds of startup. I haven't seen my engine light in about 700 miles since I swapped the O2's.

Before:
Filled up the tank, got 260 miles before the low fuel light started to flash.

After:
Filled up the tank, got 374 miles before the low fuel light started to flash.

Both cases were primarily highway driving from 60-90MPH.

One thing I should note is that I still have the catylitic converter on my car... The operation of the cat. increases the exhaust temperature before the cat.

Removing the cat. might result in brief periods where the O2 sensor would cool and stop responding, but most people with EGT gauges say that even at idle with no cat. exhaust temperatures never drop below 600 degrees F.

[Robb]

From looking at a schematic it looks like the green wire on the front o2 sensor and the yellow wire on the back one are the wires which go into the PCM. I take it that these are the two to splice into one wire o2 sensors? I have been getting a CEL for my rear o2 sensor inversion error. I think I may give this a try. I have not looked at the connector too closely yet, but do you think it would be possible to just fabricate some type of connector out of the crimp on types to make use of the existing connector without removing any of the wires?
--Robb

[spada]

Originally posted by Robb
From looking at a schematic it looks like the green wire on the front o2 sensor and the yellow wire on the back one are the wires which go into the PCM. I take it that these are the two to splice into one wire o2 sensors? I have been getting a CEL for my rear o2 sensor inversion error. I think I may give this a try. I have not looked at the connector too closely yet, but do you think it would be possible to just fabricate some type of connector out of the crimp on types to make use of the existing connector without removing any of the wires?
--Robb

there are no green or yellow wires on the oxygen sensors at all. those are just the colors that the wires are once the signal reaches the PCM. the two sensors only send that signal to the PCM. like Ryan said, the others are just there for heating the sensor up, and for the ground. you don't have to fabricate any kind of connector at all.
your current o2 sensor will have a plug attached to it. with the 1 wire, just splice the single signal wire into the signal wire on the plug (that should be gray or blue right?) then just plug it in.

[Omaha95PGT]

Do you have a part number for that O2 sensor or a specific car make, model and year to use on the PGT?

Too bad you don't have a A/F meter. It would be interesting to see when the O2 sensor becomes warm enough to become fully functional.

I heard that it takes about 30 sec for the regular 4 wire. Watching my A/F meter, it looks to be about 1 minute for the O2 sensor to get to it's full sweep.

[Jeff L]

Pffft. That's nothin'. I can handle the 1 minute full rich mode. Kinda pissed I just spent the coin on friggin' 4-wire sensors though.

Eh well. Next time, right? Great information to know, regardless.

[Ryanpzz]

You don't want to look at the wires on the existing O2 sensor harness for color codes.

What you want to look at is the connector on the vehicle harness. Wire you want is the O2 sensor ECU input wire. The right O2 sensor input wire is Black/Yellow (that is black with a yellow stripe), and the left O2 sensor input wire is Blue/White.

What I would do.. is pull the old (bad) O2 sensor off the car, and cut the wires so you have the old sensor connector and as much of the wiring on it as possible. Then either buy a Universal one wire O2 sensor (comes with it's own crip connector and heat shrink tubing), or you could get a O2 sensor for a 84 caprice... I believe they are cheaper but you'll need your own crimp connector or my favorite solder and heat shrink.

After you get the new O2 sensor and have the cut off harness from the old O2 sensor what you want to do is identify which wire on the old sensor's harness is the one that you want to connect to the new sensor's single output. To do this you want to match up the wiring on the connector to the wire colors from the harness on the car, that way you'll be certain to get the appropriate wire regardless of who manufactured the old O2 sensor (different manufacturers use different colors for the sensor output). After you've found the appropriate wire, connect that to the new sensor output by stripping the two wire ends and either soldering them or crimping them together. The other three wires can either be removed from the connector (a little tricky but recommended) or you can cut them short and tap them off. It is important to isolate each wire seperately, because two of them are the heater wires and are connected to the main power relay to the ECU; shorting them will blow a fuse and the car will not run. Then tape it all up, put the sensor in, and plug it into the harness.

What I did with mine is I tapped a wire into the O2 sensor and ran it up near the battery. That way I could check the O2 sensor voltage to make sure it varies. I checked it again yesterday and from a cold start it takes about 30 seconds for the O2 sensors to start responding (mind you this is the one wire sensors that I bought new, and they are not heated). By responding I mean they show approximately .3-.4 volts at idle, and when I manually revved the engine by hand actuating the TB valve, the voltage would go up to about .7. That's on a 0-1volt scale 0 being lean and 1 being rich, so the numbers I'm getting seem appropriate.

[StreetThisMX6]

So was there a part number for the o2 you bought?? Thanks!!

[ouch1011]

So, what would be needed to make sure the o2 was well grounded? This would be important, since a bad ground would change the voltage reading the computer receives and change its perceived A/F ratio...

[spada]

it should be grounded already since it's screwed into the exhaust, which directly bolts onto the head, which should already have a good ass ground.

i am not completely sure, but that's how i see it. the signal it sends out is the voltage difference from gound, and Ryan said the voltages are coming out perfectly normal, so it seems like it's grounded nicely using the exhaust.

[ouch1011]

I suppose that is all fine and dandy, as long as the grounds between the manifold and the block are good...

I would think that it may also be a good idea to run a ground wire/strap from one of the exhaust manifold bolts to a chassis ground or to the neg. bat. terminal, just to be sure...

But, I may be looking at replacing my O2 sensors here soon, so I might have to consider this... The price is too good to ignore...