Thread: Header o2 Sensor Code P1133 Help

Car: 2003 GTP...107k miles, original o2 sensor to the best of my knowledge. **Still getting awesome mileage, leading me to believe it's fine.

So everything was fine and well with my car until we installed headers. I, of course with no cat, got the P0140 code. That's fine.

But I also got DTC P1133 HO2S Insufficient Switching Bank 1 Sensor 1...

So yeah. I used a zzp extension harness. I did not beat in the firewall because it didn't seem to hit, as of now theres a few centimeters between the sensor and the insulation in the tunnel, moved the engine all the way forwards and backwards and it never scraped, so I assumed it was good to go. Plus, if it hits, it's hitting insulation and not metal so I figured false kr wouldn't be an issue, and it doesn't seem to be either.

BEFORE the headers, I did not have any trouble codes at all.

Mr.OtherNick said this code is normal from headers. And I've heard from two others that regardless, I should never have any front o2 codes. And so I'm just confused.

So do I replace the sensor? Try to beat in the firewall? Tune the code out?

If replace the sensor, I have heard that ngk/ntk is a shorter sensor thus more clearance. But I also hear ONLY denso/delco sensors. Thoughts??

Thanks guys!!

Just delete the code. I spent months trying to fix mine to no avail

Originally Posted by matt5112

move the O2 sensor.

a realistic answer, please?

nahh. im not moving it. dont like people touching my car, you know this.

Mine tossed the code in the collector, Mine tossed the code in the crossover aswell where it currently sits

**just figured i would update in case someone else goes through the same situation when they do headers.

once we got my car on a tuner, it reveled the o2 sensor was functioning 100% properly, so indeed the P1133 code was due to the headers and not any fault of its own. removing the code with a tuner turned out the light.

Ok... lol, I'm getting this code now with my recently installed headers (Pacesetters).

I'm thinking to switch out the front/rear O2 sensors and see if I get the same result (verify sensor is working). The O2 sensor is bouncing all over the place in the readings/gauges at idle or throttling too. Only WOT it stays steady (8-9).

So, in addition to the headers being new at the same time I installed the Overkill tuned pcm. I've got some knock readings now, small, but it pops in and out. I changed plugs and now using AL104's gapped @ .52, had the 604's at first gapped .55, but the 104's took off about 2-3* of knock.

Ok, so now the questions... is the O2 bouncing all over effecting the fuel/timing and contributing to knock (lean/rich)?

Is knock supposed to be constant, or will it appear and then disappear just as quick?
Is it possibly a false knock reading. Only thing close that I could say to hitting is the top of the collector flange/floorboard, or the power steering hydraulic lines passing just underneath. The sway bar is flipped and clear.

I don't hear any exhaust leak, had a small one at the EGR/Header tube connection and fixed it, but if there's a small one, can it contribute to the bad readings? Wouldn't the leak then need to be ahead of the O2 sensor?

Yes, I know... Pacesetters, but I band clamped and Copper RTV'd the hell out of them. Like I said, no leak that I can see, hear or feel.

All in all, if it's not effecting the knock or fuel ratio's then I really don't care. I'll address the knock through other means. I just don't want to shotgun parts at a problem (new sensor) if it is a common thing with header installs.

Matt, can you elaborate about moving the O2 sensor...?

Anyways, thanks for reading and any input you might have.

Well. I'm sure someone else can tune in better about how the o2 sensor affects the timing and fueling and junk.

But from my understanding, an active o2 sensor is GOOD thing. The reason it throws that code from my understanding is the location of the o2 sensor or the added exhaust. Either way, if your o2 sensor is good, toss the code. Secondly, blips of KR is not uncommon. be glad its not a steady 2-3* it could be false, but as light as it is i just imagine it's legit. i didn't bang in my firewall and mine clears just fine so who knows.

o2 volts will always bounce from 150-800ish when just bumming along or at idle and will dial in around 940's when WOT.

The 1133 code will be there more a while, then atleast for me, it stops running that check and the code never appears again.

Originally Posted by brandonl2000

Well. I'm sure someone else can tune in better about how the o2 sensor affects the timing and fueling and junk.

But from my understanding, an active o2 sensor is GOOD thing. The reason it throws that code from my understanding is the location of the o2 sensor or the added exhaust. Either way, if your o2 sensor is good, toss the code. Secondly, blips of KR is not uncommon. be glad its not a steady 2-3* it could be false, but as light as it is i just imagine it's legit. i didn't bang in my firewall and mine clears just fine so who knows.

Thanks for the reply!

Yeah, the Knock is weird, will show but not steady. Scan at 1 sec intervals will be like this...
0,0,0,1.4,2,1.8,1,0,0,0,0... seems to be top of gears and also a few times while in high gear and slowing down (+load) while climbing hills.

The O2 is clear of the firewall side (underneath).

Originally Posted by Fivefingerdeathpunch

o2 volts will always bounce from 150-800ish when just bumming along or at idle and will dial in around 940's when WOT.

The 1133 code will be there more a while, then atleast for me, it stops running that check and the code never appears again.

Interesting... and thanks!

maybe then I should stop resetting it, lmao!

That KR seems legit. The KR at the top of shifts might be torque management settings.