Okay, so IM getting a code too high voltage for two front o2 sensors. Could this be because:
A: both of them are picking up for the entire a/f ratio.
B: no Cat.

Im thinking A.

So Im thinking how Can I cut the voltage in half... Can I splice in a resistor some where in the wire or what? I would like something not huge, I know you can use a transformer... but is there other options?

Chris

 

Had this problem with my 98 V6. Believe it was a PO 138 code (in my case downstream voltage too high into ECM) Checked with a mechanic and said it sounded like a short/wiring problem so I unhooked rear sensor and a clip and pulled whole harness out the drivers side. As soon as I started peeling back the plastic "snake" 2 wire ends came poking out. I believe it was the "automatic shutdown relay" wire which I take to be the preheater. Fixed wire and that was that. I know it is a shot in the dark but thought I would reply anyway

 

doesnt a high voltage code mean a open circuit and a low voltage code would be a short circuit?

 

Well IM getting the same code for both o2's Im thinking it's cuz they are reading high. But im not sure.

 

It was a high voltage code (if I remember 6 volts or so into the ECM - only supposed to be in the decimal points ( I really can't explain why the wire broke there. The break in the wire was kind of "powdery" and it wasn't pinched or shorted) I am not sure if the code you are getting is exactly the same as I had but if so maybe some of the wiring for both of them is on the same circuit. I am sure there are several codes related to O2 voltages. I didn't study them. I have the full chassis manual and there are 6 pages of codes (all)

 

Ah I think I figured it out. o2 is high because --> intake plenum is leaking I got the new plate just need to install it. Hopefully that fixes it but sounds like that can make it run rich.

 

I had a high voltage code for mine and replaced the 02 sensor and it was fine... it's possible you have a broken wire or a short somewhere but I'd start with just replacing the sensor, don't read too much into it.

 

One of the sensors is new, the other one is old. Both reading the same. Makes me wonder...

 

Anyone know the voltage the computer is looking for with dual o2 sensors?

 

What kind of gas do you run? A lot of things can affect why 02 sensors fail. If you have a leak in your intake manifold then your vehicle will run lean, The 02 sensors will read that and try to make up for it and run more fuel to the engine. The extra added fuel burning through the exhaust can foul the 02's causing them to go out. Also I don't know why you would, but if you run race fuel or anything like that it also ruins 02 sensors.
(I've heard of people running race fuel to get, "a little more power")

If they're reading high voltage is more than likely means your vehicle is running rich, which would make sense if in fact you have a leaky intake. (if it's leaky after the MAP/MASS sensor)That would cause a lean mix and the 02 sensor will compensate with adding fuel to make it rich causing high voltage in the sensor.

Once you get that fixed your vehicle should be able to produce a correct air fuel ratio.