ok, background.. car is a 1996 civic dx with b16a2. harness was swapped out to a 00 si harness (complete.. everything.) car is running p2t ecu. now the problem.

on first start up, i had a CEL for '1 O2A - Oxygen sensor #1 ', and '10 IAT - intake air temperature sensor '.. both were replaced with brand new OE parts. after about 15miles i had a CEL for '61 Primary oxygen sensor' pop-up.

the o2 was just replaced with a brand new DENSO sensor from the dealer.. but, could it be bad still?

someone please help and point me in the right direction, i'm not completely car stupid, and i know a little about what i'm doing since i did the swap by myself.


Thanks,
Steve.

EDIT:: all pre-o2 gaskets have been replaced.. zero exhaust leaks from my knowledge.
seems to get it more on cold starts (ex. start the car cold.. instant CEL, but then let the car warm up, reset the cel.. wait a while, start it back up, no cel for 100-150miles+ sometimes, other times.. within 15miles.)

ALSO:: code is a P0133 slow primary o2 response.

 

Check for an exhaust leak.

 

Pre-o2 right?

So, either where the header bolts to the head, or where the header bolts together? I'm using the OE b16a2 exhaust manifold. Thanks for replying Ron.

 

Correct, near or upstream of the primary O2 sensor.

 

ok, there is a leak where the manifold goes together, how can i fix it? just order some new gaskets and good to go?

 

Together with what? That's the cause of the CEL. Can you post a picture of the manifold area that's leaking?

 

where the top half meets the bottom half, lol. im not sure of the technical term? well anyways.. the photos!

 

That's where exhaust pipe A and the header connect. You need to replace the two gaskets and possibly the three nuts. Also make sure the nuts are torqued to spec.

 

ordered them, now i get to play the waiting game. so do you think after fixing that, i should no longer have a CEL for primary o2.

i dont want to get over excited, but my car has had a cel on since i got it with the d16y7.. i need it gone so i can REF it and be legit. if this doesn't cure my problem, any other suggestions?

Thanks again Ron.

 

Repairing the exhaust leak has a very high probability chance of fixing the CEL. Your gas mileage should also greatly improve. Hopefully the cat has not been damaged.

 

i've driven it like this for about 800miles. hopefully i do not have to buy another cat.

 

My stupid EM1 has had a CEL for the primary sensor for like 30k miles. I've tried replacing the O2 and everything else. The O2 sensor becomes char broiled in like a month and now I have a CEL for teh cat efficiency.

It has a 1 peice header on it. I don't hear or smell any exhaust leaks....

Whatever.

BTW, OP, you should try buying the SAME O2 sensor from an aftermarket source. You can get them for much cheaper. www.sparkplugs.com for example.

 

maybe you're running rich.
and yeah, i know i can buy the same o2 from them at half the price. what can i say, i like to waste money i don't have.

 

so, i changed the gaskets.. and after about 30miles of normal highway driving, and then streets on the way home... BAM! light again.. same thing 'CEL 61 - primary oxygen sensor'

any other suggestions?

 

Are there any other codes besides code 61?

 

no other codes. its really bugging me, i need to get my hatch legitimate. any ideas?

 

Do you have any exhaust leaks between the primary and secondary O2 sensors? This could also throw code 61.

 

i doubt it, those gaskets have been replaced, and so has the hardware.

 

 

maybe its time i get another primary? ugh.. my wallet hates those.
EDIT:: maybe my secondary is bad? and its causing the ecu to think the primary is no bueno?

 

The secondary O2 sensor is likely fine. Given that your primary O2 sensor is new, I think you still have an exhaust leak somewhere between the first and second O2 sensor.

 

hmm.. i changed all those gaskets and the hardware, but maybe something isn't sitting right, ill have a look at it tomorrow when the sun's out. hopefully i can get it straightened out.

Thanks for your help.
if there isn't a leak and i still have it, any other suggestions? push my car off a hill on fire?

 

Not just yet. I think you'd relook at the O2 sensor, but spend some time ruling out an exhaust leak first.

 

ok, so im back.. still having trouble with this code. all gaskets changed, all hardware replaced, everything torqued to spec..

the code is the same.. 61- primary o2, pulled it up on a scanner and its a "P0133 - Oxygen Sensor Circuit Slow Response (Bank1, Sensor1)" checked all my wiring, it all looks perfect.. i heard it might be cause by a slight vacuum leak?

any help is greatly appreciated.

 

You might now want to try swapping in a known good O2 sensor.