So here is the story. My friend has an integra GSR. his midpipe (i think that is what it is, its the pipe behind the Cat) broke. his exhaust was then hitting the ground and sparking and stuff... but no CEL on yet. His dad said for Christmas he would buy him the parts if he put it on himself or paid labor. So my friend ordered this tanabe cat back exhaust. it seems well made. after putting it on we got a CEL. it would go on and off every few days. Now he left on vacation and let his girlfriend use his car. So now we are going to fix his check engine light while he is gone. The code is p0135. Heated 02 sensor bank 1 or whatever. So i tried reading around and some people say replace the sensor. others say its the heater circuit. I dont think we are idiots i just dont wanna replace stuff that i dont need to. And like i said its not my car so Im not going to rewire stuff or anything. I would just buy a new sensor at the dealer if that is what it needs... I know you guys cant say for sure, but is it more likely the wiring or the O2 sensor or something else. And is there a thread of how to install the bank 1 o2 sensor, just cause i dont actually know where it is... but i havent actually looked either...

 

Primary O2 sensor heater circuit is the issue. Replace the sensor, reset the ecu and the code will go away. It's really not an issue though. When the sensor gets some miles on it that heater wire gets very fragile and sometimes just knocking the sensor the wrong way will cause it to break and it will throw a code. The wire is inside the sensor btw. I'm sure when the exhaust broke it jarred the wire and when you guys put the exhaust on you knocked the cat once or twice and the wire finally broke. Back to where I said it's really not an issue. The heater just gets the sensor hotter quicker so the car gets into closed loop sooner. It's not totally necessary. If you really want to change it out, get a denso primary o2 sensor from www.rockauto.com You will find the best price there. Denso is factory replacement and the only company I use for replacement honda electrical parts. Probably about $40-$50 on rock auto vs $90 or so at the local autozone for a shitty bosch sensor.

Also, it's the pre-cat sensor. The connector for it should be attached to the back of the engine block via a metal bracket if the car hasn't been fucked with too much.

 

it is actually a bit of a big deal. without the heater for the o2, the ecm won't go into closed loop at idle. it actually won't go into closed loop a lot of the time. that's why the single wire non heated o2's were completely obsolete. with the heater, it only takes about 45 seconds, on start up, for the ecm to go into closed loop.

OP, if you want to confirm the problem for sure before buying a new sensor, swap the primary o2 with the secondary and clear the code. if you then get a bank 2 o2 code, you know the o2 sensor is done. that is, assuming this is a 96+ car

 

 

So back when the heated o2 sensors were non existant, the cars all just roamed around in open loop all the time...Right, because that makes perfect sense. As soon as the o2 sensor is heated appropriately via the exhaust gasses the car goes into closed loop. The o2 heaters are just so the car gets into closed loop faster.

 

First before you spend any money do a little testing. First reset the ECU and see if the code returns. If it does check all the wiring going to the 02 to make sure it hasn't been damaged. Finally check the resistance on the 02 heater wires., if they aren't in spec replace the sensor

 

yes. they actually were in open loop a lot of the time. definitely in idle. and sometimes at low cruise speeds. this is especially true for hondas, since they tend to run on the rich side in OL which keeps egt's down. and yes, we used A LOT of techniques prior which would be looked at as ridiculous by todays standards. and we will continue to do so with techniques used today, and in the future as well.

you've got to remember, from what these systems evolved from. it wasn't that long ago that we were dumping raw fuel into cylinders that went straight out the tailpipe without ever being combusted. having feedback, even if only part time, was still a huge step forward from having none at all.

OP, if you want to test, it's easy. KOEO, check for voltage across the heater circuit ground and power wires at the sensor connector. if you have voltage, the sensor is bad. if no voltage, back probe at the ecm connector.

 

All of these refinements of these conponments are for one sole reason

reduced emissions,
reduced fuel consumption,
reduced noise

Automakers will constantly be finding ways of doing so like varible displacement, varible valve timing ect.

Although Honda is reluctant to upgrade until forced, very primitive system compared to most other makes and models of the same period. But they were the ones that pioneered Vtec, although it is also primitive compared to others VVT

 

eh. i wouldn't say primitive. simple, yes. but it's that simplicity in engineering that made hondas what they are. toyota had cam phasing for ages. dual intake runners, etc.. but to be able to manipulate valve lift was really a breakthrough. and they did it with such a simple system. and honda compounded on that with the introduction of i-vtec. combining cam phasing with their traditional variable valve lift system. and even that system is over a decade old! the **** evolves so rapidly these days. i think that's one of the major challenges to this trade. keeping up to date with what's out there.
i do agree. honda, and for the most part, a lot of japanese manufacturers are pretty far behind in the networking and communication/software side of things compared to domestics. but honda definitely is the most far behind in that category.