94camaroz28lt1

iTrader: (1)

O2 sensor heater problems?? should the the heater always be on with the ignition or should it only be on when the sensors are cold or idling for a length of time?



Here is what I have discovered so far error codes P0134, P0154, P0174, and heater O2 codes PO300 random misfire. I also have long tube headers high flow cats and dual 2.5" tail pipes 4.8L V8 swapped into 04 Colorado.


I think the wires are 16 ga but 18 will also work fine, the wire I used on bank 2 was, 22 ga or smaller.. my bad it looked the same size but had thick insulation! I switched it to 18ga and Po174 went away.

Well on to the switching issues. mine would swtich between 450mv and 630mv , when hot and around 450-470mv when cold. I also got a random O2 sensor heater circuit code. I checked the O2 senor in place back probed it the the key on and got intermittent 12 volts. So I cut the O2 sensor heater ground and wired it right to chassis ground, this improved the range cold was 300mv-800mv and hot was 100mv-950mv huge difference, but would through a code for the heater circuit, so I wired in a spare dummy O2 senor into the computer side heater circuit, and kept my O2 sensor in the exhaust heater ground right to chassis ground, worked great no codes, runs much better.

Well I thought must be bad wire connection the PCM I replaced the heater circuit pins and reconnected the O2 sensors back to factory spec... no change!! So I cut both sides ground and wired them straight to ground, and wired in two spare O2 to the computer side!

The truck as never run so good, and no codes what so ever! As far as I know the heater circuit on the O2 should allays be on with the key in the run position, so I don't know what is wrong?? I think I could get away with a way with a O2 fooler or a resister of the right ohms and watt in-place of the spare O2 sensor, this doesn't seem right, but works??

I wonder what your O2 sensor logs look like? I wish I new if this is from long tubes ..... sensor can't get hot enough gas flow to fast on idle?

Or bad PCM heater control circuit. Does anyone know if the O2 heater ground is supposed to be constant or is it a Pulse width modulated signal? I got what seemed to be a PWM signal, which didn't seem to work well, am I harming anything by having the heaters always on, or is this how they are supposed to work?

flame

iTrader: (13)

On older systems they had the heater on all the time the key was on. Most of the newer stuff is using the pcm to control the heater to help prolong the sensor life. In your case the pcm strategy to heat the sensor is not working well enough because the sensors are farther down the pipe and don't get as much exhaust heat. The way you have it isn't gonna hurt anything other than if the sensor that is in the pipe has a heater failure you won't get a code for that. You would likely get one for no switching though to lead you to it. Hope that helps

94camaroz28lt1

iTrader: (1)

Thanks a lot!! How much will this take a way from the senors life? Is this a common problem with better flow-wing exhaust high flow cats, and long tubes?? Do you know what size a resister I could use in place of a O2 sensor.. basically a O2 fooller without O2 part just the heater fooler?

flame

iTrader: (13)

Yes it is common for the sensor heaters to set codes when location has changed. The pcm looks for an amp draw on the heater circuit so I don't think you can fool it with a resistor in this case.

94camaroz28lt1

iTrader: (1)

Well I went to attitude shack aka radio shack, which they now call Source here in Canada, anyway one of the brain dead associates led me to there resister pack, "this should work" well it fried that poor little sucker, I found out now that it should be a much large resister! It should be one 20 ohm 20 watt resister or two 10 watt 10 ohm resisters wired in series.

None of this matters as I was able to turn off the heater circuit codes via HP tuners.. Hp tuners to the rescue again! I wired the ground from bank 1 sensor 1 and bank 2 sensor 1 together, and then to chassis ground, turned off the heater circuit the codes for bank 1 sensor one, and bank 2 sensor one. So far so good, hope it doesn't lessen the life of the O2 sensor to much?? If I can get 80,000 kms out of it I will be happy! 80,000kms is half the expected life span of a modern O2 sensor at 160,000kms

Mike454SS

iTrader: (4)

LS1 F-Body's power the heaters off an ignition switched wire, the PCM isn't in control of it on them. I actually use the rear O2 heater power and ground for my wideband controller power/ground.

A lot of newer stuff is, including I believe some other 0411 controlled vehicles, but not the F-Body.

flame

iTrader: (13)

Yes I am fully aware of that. 2002 is now considered old. This guy is running a 4.8L in an 04 Colorado that has pcm controlled O2's.

94camaroz28lt1

iTrader: (1)

talked to a few shops today, told me this is normal practice with a LS2 and long tubes, said my sensors will still last a long time, and not to worry about it!! as long as you turn all the sensor 1 O2 heaters off with HP as well, or the computer will go into open loop mode.

Monte4ever

iTrader: (2)

Would a rear O2 sensor from the C5 Corvette work? From my understanding they flash quicker and excuse me I'm a newbie.

94camaroz28lt1

iTrader: (1)

While possible, I believe the rear O2s are meant to be slower reading, and front ones switch faster and have more range, also coming from newbie!

I think I am better off just leaving it the way I have it, if they crap out quickly hen I may switch to a older 4 wire O2 that was meant to to b on all the time, the universal ones that guys use when switch from none heated to heated, or 1 wire two three or four wire. When the upgrade them they just switch the O2s on with the ignition and they stay on constantly.

FYI

1 wire; signal, grounds through exhaust sytem

2 wire; signal, and ground, doesn't ground through exhaust system

3 wire; signal, signal ground through exhaust system, heater positive, and heater ground,

4 wire; signal, signal ground, heater positive, and heater ground