Zac W.

Took my 99 integra to my local auto part store to have them check out why I had a check engine light. Came back and said it was bank 1 o2 sensor. He told me it was the upwind sensor. So, I replaced it with a brand new one. I'm still getting the same check engine light with the same code. What's going on? I have an aftermarket header with 2 1/4 in exhaust to a vibrant muffler. I have no catalytic converter. I had to make my own bung for the upwind sensor right as the 4 header pipes go to 1 pipe. (why there wasn't one to begone with, I don't know) and the downwind sensor I didn't have to mess with.

Any suggestions on what may be the problem?

Thanks!

HondaPartsHero

Post the exact code should be like Pxxxx where the xs are numbers

Zac W.

The code is P0135

el crapitan

if you've got no cat, you should be throwing a secondary o2 sensor code as well. is the secondary sensor rewired? has any of the wiring for either sensors been messed with between them and the pcm?

Zac W.

Not for sure. Haven't got that deep with it. The guy I got it from was a big tuner guy so maybe he did something like that. I just don't get it. Maybe the NEW sensor I just put on is bad?

el crapitan

could be. more likely you have a wiring/connection problem though. ignore my previous comment about piggybacking the secondary o2 off the primary. that's a method used on jdm non obd pcm's with dual o2's. i was confusing the situation.

but anyways, what i'd do is get a wiring diagram for the heated o2 circuit and test continuity of the heater wire between the o2 sensor and pcm. if no continuity, find and repair the damaged area of the wire. which could include a connector, so check the pins to make sure there's no backing out.

question though, did this problem just start occurring after the header install?

Zac W.

Ok I'll see if I can find a wiring diagram. When I bought the car a year ago, it already had the header and exhaust on it. The CEL has also been on since I got it

fcluddington

do you have to pass emissions or are you just tired of the check engine light on? How is the fuel economy?

TheRealTegger

P0135 is the sensor's heater circuit. Either it's not working, or the wiring is bad and the ECM can't see any current flow on that wire.

beecee18

Zac W.

I think I could get a little better mpg. I think last i checked i was at 27 mpg. Thats mainly ALL highwy. And yes I'm tired of looking at the CEL. Lol

Hopefully I can check for continuity today

beecee18

The only way you lose fuel effiecency is because the heater circuit if not working properly does not preheat the O2 sensor, The sensors love heat and work more effiecently under lots of heat, so you will find the. vehicle to be uneffiecent after startups, coldstarts, ect. The heater is simply there to simulate the heat generated under normal driving conditions.
After the vehicle has reached operating temp, the sensor will begin to be effiecient, so yes you are probably losing a miniscule amount of mileage

el crapitan

if the pcm determines a fault with the o2 sensor, it remains in open loop. that is, no feedback from the o2, regardless of engine temp

beecee18

lol,
the code is simply for the heater circuit
the sensor still recieves the signal from the o2
And streams feedback to ECM for closed loop operation
A heater fault would not run the vehicle in open loop constantly

please remember bud this isnt caveman OBD1, this is OBD2 where there is redudndancy so this doesnt occur. research OBD2 some more.

and it is a ECM(engine control module)

not a PCM(powertrain control module) as these dont control transmissions and arent linked to BCM's ect. only engines.

el crapitan

my apologies. i stand corrected.. on both accounts

beecee18

no worries,

As this is how we learn, you will catch me some day for sure as I can be a loose cannon. And I will be thanking you