OTECTom

I have been driving on a consistent check engine light for over a year now. I wouldn't care, but I need to get my car inspected.



The CEL shows O2 sensor codes (I don't know which codes specifically, sorry). I assume this is because I am running a cat-less header. I have tried to "trick" the computer by placing the rear O2 sensor on two of these spacers.







These spacers are meant to trick the O2 sensor into thinking it is behind a cat by restricting flow, but I am still getting a check engine light. Any suggestions?

Rd1cuda

More then likely either the front or rear O2 sensor needs to be replaced or maybe both! You just have to find out what codes are exactly coming up. In order for you to use that foul plug both O2 sensors need to be working properly! So try to find out the code number. I had the same problem. Come to find out i had to replace both sensors.

faithofadragon

is the first o2 at a junction between all 4 primaries also

HyundaiKitCoupe

if you take the cat out, then you will get those codes. you need a high flow cat and an O2 spacer (in which it will still be a hit or miss) or put the original header back on.



funny thing i have a high flow cat with an O2 spacer, and the codes pop up several miles after all of the Drive Test Cycles have been completed (you need a code program and an OBDII - PC reader to see if all the DTC's have been completed) it's through that gate that i've been lucky enough to pass inspections lol.



i've tried everything, and only the O2 spacer works, but only for some time before the CEL pops back on.

faithofadragon

when i had a header i NEVER had a CEL



no bullshit spacers, no cut and extended o2 sensors and a carsound cat



i placed one o2 sensor on the collector of the header, i pulled the o2 sensor harness apart and rerouted it so i can have the 2nd o2 after the cat



theres about 3 feet of extra wiring in the harness

HyundaiKitCoupe

^I recollect you mentioning that! Years ago Odessitpashka told me the same thing. Strange, but he had like 40k on his engine. I've tried everything. All DTC's pass. Maybe 30-40 miles later CEL comes on...



I extended my post-cat sensor with 3 feet of extra 16 gauge wire to the bottom of the car where the cat is.



If you fail emissions, they will give you a 2 year extension. Or you can extend it online yourself. Before I figured my "CEL pattern" out, I had extended my deadline 1 year personally, and 4 years electronically. Electronically was less shameful lol.



This is the scantool I use by the way:

OTECTom

Wow, seems like a struck a nerve in here of a common issue of tuning these cars.



For the record....



1. Both O2 sensors are brand new.

2. O2 sensor #1 is in one of the four header tubes (the one farthest from the fan belts)

3. O2 sensor #2 is mounted just after the flex pipe

4. I know it's meaningless, but I am running a high flow cat, but it is further down the exhaust.



Funny thing is that I was running this same setup in my A/T tib, and rarely ever had a CEL on. Now in my M/T tib I can't get it to stay off for more than a dozen or so miles. I'll get the codes scanned tonight and let you know what they are.

faithofadragon

yup thats your issue, o2 sensor 1 should be where the flex pipe is and o2 2 should be after the cat



dont need to extend wiring like hkc did the resistance in the longer wiring will get ya



oh and BTW one easy way to cheat to get the first o2 sensor relocated is to run 2 rear o2 sensor styles



you gotta realize man ive answered this question roughly a gazillion times and no one seems to listen



THERE IS NO NEED FOR DEFOULERS, NO NEED FOR EXTENDING THE WIRING YOUR FACTORY EQUIPMENT WILL WORK JUST FINE



one of these days ill have to go to the junk yard and do a write up

OTECTom

So wait.....



You're telling me that if I move my first O2 sensor to the flex pipe, and have a bung added for the second somewhere after the cat, my light should stay off, AND I won't need to extend my wiring to do it!?

faithofadragon

YES THAT IS EXACTLY what im saying



now you get it