Both upstream O2 sensors are popping circuit codes??

[rsblankman]

I have a 2001 Pontiac Trans Am WS-6 manual-trans that is bone stock besides the intake and exhaust with around 85K and it is popping both upstream O2 sensor codes P0134 and P0154 for "low or no circuit activity". I have recently replaced all four of the O2 sensors with Denzo's because I was getting a code for just one, but wanted to perform some preventative maintenance( what a BIG help that was!!!).

POSSIBLE SYMPTOMS:
- if I clear the codes while driving, they stay off until I turn it off, restart, and start driving again...?
- after idling while parked for 5-10 minutes, when I rev it up, it pushes out a little white smoke, but never anytime else...?

RECENT MAINTENANCE PERFORMED POSSIBLY ASSOCIATED:
- Fuel Filter Change
- Full Cold Air Intake Installation and (cleaned the throttle body)
- Changed All (4) O2 Sensor with Denzo's

Please help?

[tatertot91]

I would plug a scanner that reads live data and see if the upstream o2s are reading anything at all. When you say exhaust does that include headers?

[rsblankman]

Right, I actually had one of the head guys that designs the diagnostics for Snap-on tell me to run in lean conditions and then in rich conditions to see what come up on the scanner, but my question is if I can clear the codes and drive for hours, and no code comes up again, wouldn't that mean the O2's are working? I mean what are the chances that both of the new O2 sensors are defective?? I do not have headers, just high-flow cats back...

[tatertot91]

Clearing the codes just gets rid of the trouble codes. The fact that it doesn't turn on immediately doesn't mean that the o2s are working, just means the computer hasn't recognized the issue yet. I still recommend monitoring the sensor activity on a scanner. They should be switching constantly while the car is running. If they are switching slowly or not at all there may be a wiring issue or a faulty sensor, live data would be the best way to troubleshoot them.

[SMWS6TA]

tatertot is talking about open vs close lope. In the beginning the ECM doesn't take account of the o2 readings till the engine reaches operating temp. From there it makes adjustments based on the o2 readings. If it isn't receiving data pops code.

Have you checked the O2's yet? followed the wire harness to make sure the headers haven't burnt a wire or two?

[SteveC]

I had one of my 02 sensors replaced, don't remember the code, the culprit was the electronic part installed on top of the sensor. Of course I could not purchase just that part, I had to purchase the entire 02 assembly.

SteveC