MAXXLIMIT

iTrader: (16)

I have a SES light on for P0134, P0135, P0154, P0155. I had these same codes thinking my o2 Sensors were bad. Replaced them both with New Bosch sensors. I cleared codes and comes right back on. So I checked power to the Heater 02 fuse and gets 13.0-13.5 volts. I do have longtube headers, I have a 2002 pcm swap in a 98 firebird. The only other things im thinking is check the ground connection behind the driver side head and check the pins to the pcm.

Now would having a 160'f thermostat and the fans programmed to come on around 170'f and 175'f and the temp of the car stays around 170-175'f would that affect the codes because not getting hot enough for the o2 sensors? If I take my o2 sensors off and check to see if they heat up that means the ground is good right?

Help is needed and would be great. Thanks!!!!

rel3rd

iTrader: (43)

Had the same issue with my truck, also after longtubes were added.

I simply changed those codes to No Error Reported. The sensors switched fine, just not quite as fast as with stock exhaust. No issues since.

Just was looking at your sig and can't help but wonder why with all the mods and rwhp you have, your car only runs the same exact times as my baby cammed 3755# race weight (me=290#) Camaro ran with 75+ LESS rwhp? Is that track in super high elevation or something? Not trying to diss your car at all...just curious, that's all.

94camaroz28lt1

iTrader: (1)

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?

105

iTrader: (7)

I am having the same problem as OP after installing headers. Are most people just changing them to "no error reporting"? Is that safe? A couple guys on hptuners told me I need to keep those on. This was after I disabled them to get rid of SES light.

105

iTrader: (7)

Nevermind I guess. A guy on hptuners just told me these codes are normal after headers and to just disable them.