I swear after installing these headers, it seems nothing has been the same on this car. To start out, I installed the headers but did not order extensions. I did my own "cut and splice" work on the old ones I had and suprizingly it worked well for about a month or two. Then I started getting the codes P0153 and P0133 (Slow responce for each bank on the precat sensors). I replaced them with some Delphi brand O2's and used 12 inch extensions that I ordered from Thunder Racing. It seemed to work fine for about three weeks, but then all of a sudden, both codes would come on and in no particular circumstance. It was totally random.

I read on the boards that any other brand other than Delco will not work well with these cars. So I coughed up and last weekend bought two new AC Delco sensors. I took out the Delphis and put in the new Delcos. Well, while I was driving home tonight, my SES light came on for P0153 (P0153 Heated Oxygen Sensor (HO2S) slow response Bank 2 Sensor 1). I just don't understand why this code keeps coming up! Everything seemed to be ok for about a week, but then it just decides to come on. I would think that maybe some wiring has been burned/crushed/damaged but that would mean it would come on as soon as I replaced the sensors, not a week later. Anyone have any ideas about this? It has been driving me insane.

 

Have you physically vefified that there is no damage to the wires? One would think this would cause instant faults. I had my knock sensor wire melted to one of my o2 wires, and my o2's were registering fine in Datamaster. I only poppped the code for knock sensor. Electricity does crazy stuff. Have you taken a volt/ohm meter to the connectors to verify coreect volts and resistance. Sorry as I don't know what those values are suposed to be. I'm sure someone here does.

 

Most O2 sensor faults are not immediate. They take several minutes to register. Be sure you have no splices in the wiring. Obviously look for wire problems.

Look for any cylinders that may not be firing on the problem side. Check for any exhaust leaks or abnormally high back pressure on that side. If all that is ok, try swapping the O2's.

And oh yeah, the GM, AC Delco and Delphi O2's are all the exact same part made by a company called Standard Auto Parts. If anyone has to buy any, get them from here. http://store.getgmparts.com/es10006.html. Sorry I couldn't tell you that intime to save you from buying more.

Dave

 

Are you using any threadlock, anti-sieze or sealer when you are installing them? Is there any possibility that you are contaminating the outside of the sensor with oil (drips from engine)? What type anti-freeze are you using (e.g. the green stuff has silicon, the orange stuff doesn't), and are you ever seeing low coolant levels? Are you using any leaded racing fuel?

 

I did not use any thread lock/anti-sieze with the sensors as it already came with anti-sieze on the treads. There is not any drips from my engine as far as oil goes but my AC does drip down my y-pipe there and it is possible that it does get my O2 wet.

I am using the usual orange anti-freeze and I have no leaks. No racing fuel, just Chevron 93 octane.

If it is a wiring problem, why would it take up to a week for the problem to arise? I will go check all the wiring, but can't you only check so far before it goes into the wiring harness? I sure hope that if it is the wiring, that it is before the harness. Of course it probably won't be....

 

Check the resistance between the O2 sensor and where it enters the pcm. You chould have no, or very low resistance.

 

How would I check the resistance? What prongs on the pigtail do I use?

 

I noticed that my AC drips on my 02 sensor. Do you think the constant dripping on it could cause a problem with the sensor maybe not getting enough oxygen to it if it is constantly wet? I checked the wiring and I didn't notice any problems with any burned wires. Could it be possible that the pigtail is bad? I know that this happened to my MAF and once I replaced the pigtail, I stopped getting an SES light for it. Also, if I wanted to check the resistance, what do I do for that?

 

I found something somewhat interesting. I had my O2 sensor unplugged and I started the engine and plugged my scanner in. It was bouncing back and forth between 0.440 and 0.445 V. Is that normal if the sensor is unplugged? I would of figured that the voltage would be 0.0?

 

TTT- I switched the sensors from side to side and the code followed the sensor over to the drivers side. I suppose there is something that is contaminating those sensors. I noticed also that the sensors are covered with quite a bit of carbon which suggests that the car is running really rich. Anyone have any ideas?

 

The PCM supplies a 450mV bias signal to the sensors. The sensor adds or subtracts voltage. You should also see 450mV when the sensors are cold. They can not generate any voltage of their own when they are cold.