Slow response O2 sensor problem P0193 - 96 GTS

[MacGyvers Mullet]

I am getting a slow response O2 error for my bank 2 sensor 1, code P0193. This is a 96 GTS.

To help here is exactly what changed before the code was thrown:

1. Cat delete pipes for about a month. Code never showed up, even after 800 miles of use.
2. Installed new Bosch upstream O2 sensors. Ran it on a dyno to get test numbers and drove about 30 miles, still no code.
3. Sent PCM to be re-tuned
4. While it was being tuned, I changed out the thermostat, spark plugs/wires, intake gaskets, and throttle body gaskets. Gaskets were installed properly (kind of hard to screw those up) and all bolts were torqued to FSM specs, correct order.
5. Installed the PCM after it was sent back.
6. Got the code within a day.

7. Took out both upstream Bosch sensors and put back the OEM sensors, since aftermarket sensors can be a bit jenky at times. Cleared the code by unplugging the battery.
8. Ran it back to the dyno for the post-tune runs. Curves all looked great.
9. Code returned within a day or two.
10. Re-sealed the cat delete pipes and visually inspected the visible intake hoses. Everything seemed to check out. Cleared the code again.
11. Code returned after three days. Each day had long distance driving, but it didn't show up until about 200 miles after the last code clear.


The tune wouldn't have anything to do with a slow O2 sensor, correct? The car has zero issues, as it runs strong and idles smooth. It never even got a code with the cat delete pipes and factory tune, which I would think would throw a code, if anything.

Any ideas or solutions? Would non-fouler O2 sensors be a solution on this code, or is that way off base? Maybe I am missing an intake leak somewhere?

[Dan Cragin]

You might want to try 2 new OE upstream 02 sensors or 2 Walker 250-24076.

[MacGyvers Mullet]

You might want to try 2 new OE upstream 02 sensors or 2 Walker 250-24076.

Hmmm, the Walker ones are fairly inexpensive on Amazon. Replace both at the same time...or be super cheap by saving a measly $24 and just change out the failing side?

[Dan Cragin]

Always change O2 sensors in pairs.

[plumcrazy]

always trust what dan cragin tells ya.

[dave6666]

Can you give more details on the P0193 code? It's an older code that I'm having difficulty finding the full description on. Post a link if you find one.

Does the code, after having been cleared, pop up very quickly after starting the car? Or later into the run?

Do you have aftermarket headers or OEM?

Per the question above, where are the O2 sensors installed?

I tried the Walker sensors before to solve an O2 CEL problem and they ended up not being the best solution as the CEL ended up coming back after a few months. Yes, the first few times I started the car it was all good, but it did not last forever. You should however try them as Dan suggested. You never know. It's a cheap test, and now that you are tuning, well, you now get all the crap that sometimes come with it. Like O2 sensors. BTW, we solved my O2 CEL problem by adding more warmup fuel during open loop and went back to the OEM sensors. But not having the full detailed description on P0193 I'm kind of limited in my responses on your deal.

The coincidence of this CEL and the tune file should not be disregarded. But absolutely don't put non-foulers in there lol. Those are to take spark plugs out of the cylinder in an engine that has serious oil blow by. The plugs can still ignite the a/f mixture without getting coated in oil and fouling. They also "fit" O2 sensors if modified, and are typically used on the rears to move the sensor out of the exhaust stream when you remove the cats. But if you did that to the fronts? Geesh lol. The fronts need to be reading instantaneous exhaust gasses for engine tuning. If you put non-foulers on there I doubt your engine would even run long. Literally. It would take a tuning induced dump on you.

Also, I run no cats and have never thrown any O2 sensor code since pulling them.

Good luck. Let us know if you find more on the code.

[MacGyvers Mullet]

always trust what dan cragin tells ya.

Truth

Can you give more details on the P0193 code? It's an older code that I'm having difficulty finding the full description on. Post a link if you find one.

Does the code, after having been cleared, pop up very quickly after starting the car? Or later into the run?

Do you have aftermarket headers or OEM?

Per the question above, where are the O2 sensors installed?

I tried the Walker sensors before to solve an O2 CEL problem and they ended up not being the best solution as the CEL ended up coming back after a few months. Yes, the first few times I started the car it was all good, but it did not last forever. You should however try them as Dan suggested. You never know. It's a cheap test, and now that you are tuning, well, you now get all the crap that sometimes come with it. Like O2 sensors. BTW, we solved my O2 CEL problem by adding more warmup fuel during open loop and went back to the OEM sensors. But not having the full detailed description on P0193 I'm kind of limited in my responses on your deal.

The coincidence of this CEL and the tune file should not be disregarded. But absolutely don't put non-foulers in there lol. Those are to take spark plugs out of the cylinder in an engine that has serious oil blow by. The plugs can still ignite the a/f mixture without getting coated in oil and fouling. They also "fit" O2 sensors if modified, and are typically used on the rears to move the sensor out of the exhaust stream when you remove the cats. But if you did that to the fronts? Geesh lol. The fronts need to be reading instantaneous exhaust gasses for engine tuning. If you put non-foulers on there I doubt your engine would even run long. Literally. It would take a tuning induced dump on you.

Also, I run no cats and have never thrown any O2 sensor code since pulling them.

Good luck. Let us know if you find more on the code.

Dave, I was having the same trouble finding any expanded information on the code. What the scanner shows is "O2 Slow Response, S1B2". Mowing through other cars info with the similar code show the O2 sensor registering at a frequency that is about at half of what it should be. The amplitude of the O2 readings may be the same, but it is the frequency that is incorrect. The good thing is that the error in the feedback loop doesn't affect driveability, but it is a PIA. I have heard it can affect MPG, but I can't confirm that for sure, or say what other side effects come with it.

The code will not pop up immediately. It takes a few runs/days to do so, all runs being full temp drives. In fact, this last time I thought it was gone for good and then it just popped up randomly after about 3 days of heavy use.

OEM exhaust manifolds, so stock location for the sensors.

Definitely won't throw non-foulers into the mix. I just saw those mentioned a few times when people had codes pop up on later Gen II's with the cats removed, but didn't research them very much. Thanks for the explanation, as I now see exactly what they are/do.

I will toss in the Walker sensors as soon as they get here. The code is a minor pain, but the pros of removing the cats outweigh that pain so far.