mustang99v6

Hello all. I recently installed some mac LT headers, mac H-pipe, removed cats. The rear two 02 sensors have been hooked up this whole time, the front two, have not. I got 2 codes after a day or so that said: O2 Sensor Heater Circuit
P0135 I'm told this code is: Bank 1 sensor 1
P0155 I'm told this code is: Bank 2 sensor 1

So, yesterday I reconnected one of the front 02 sensors. The driver's side to be exact. No cut and splice, just a longer wired factory bosch sensor. Passenger side is still disconnected until I get it lengthened.

Here is my quandary, if those codes pertain to my front 2 oxygen sensors not being connected, then the codes should have changed when I reconnected the one sensor. Right? Or, at least I should have only gotten 1 code thrown back due to the single missing sensor. So, why am I getting the same two codes?
Only thing I can think of is that the codes pertain to the rear 2 sensors throwing a code due to not being surrounded by catalytic material. And, if that is true and correct, why haven't I been getting codes thrown due to the previously missing front sensors?
Do you follow? I just want to get to the bottom of this and have my info correct when I order a tune. So, I'm thinking 4 sensors, 4 possible codes. Right? 2 connected, 2 not. I should be seeing 2 codes for the missing ones, and MAYBE 2 codes for the rears not being able to read correctly. And/or any combination of the 4 codes. So, now I have 3 sensors connected and the same 2 codes, doesn't make sense to me. Any help would be greatly appreciated. Thanks.

LilRoush

You should have had the front two connected, those are the important two. There are a few reasons the O2 sensors kick codes... not getting to the right temp, reading rich or reading lean, not getting a reading at all etc...

You'll also need to address the rear O2s since you have an offroad H pipe. You'll need MILs or have them turned off with a tuner.

mustang99v6

Yes, I know the fronts "should" be connected. I am waiting on parts to lengthen them. But, in the meantime, I had to drive the car. Plus, I'm trying to gather as much data as I can to tell the tuner. I plan on having the rear 2 "tuned" off. But, in the mean time, what do you make of my codes or lack thereof?
Should the front 2 be throwing a code when they are not plugged in? if so, what code?
Should the rear 2 be throwing a code because they aren't surrounded by cats? if so, what code? Thanks.

LilRoush

Front two not connected are throwing the codes. Just a heads up, the ECU is adjusting your A/F ratio based on wrong readings since the front two aren't connected. You are risking running lean and damaging the motor big time.

mustang99v6

Hey, thanks for letting me know that. I've only had to drive it 10 or 20 miles tops. I do have to say that it is idling better after I connected the single front sensor though. I am still curious about why I'm not having way more codes being thrown though.....

petrock

http://www.obd-codes.com/p0135
http://www.obd-codes.com/p0155


If you didn't clear the existing codes after you reconnected the sensor, then the CEL won't go away until a few on-off cycles. If you don't have the scan tool to erase the code, simply disconnect the battery and let it sit for about 10 minutes and then reconnect the battery. CEL should be cleared. Drive around for a while and see if the CEL comes back.

Either way, re-connect the passenger side o2 sensor. As LilRoush pointed out, you are risking damaging your motor.

mustang99v6

Hey, thanks for those links. That site is very informative. I do have a code reader and I did clear the codes previously, then the same two showed back up. I've guinea pigged the car to see what codes are thrown when. After reading on that site, it lets me know that obviously my rear 2 sensors seem to be working fine (for now). I do plan on having them turned off via tune. It still puzzles me though, why I'm still getting 2 codes come up. Now that I have the drive side sensor hooked up (not sure which bank that is......) I would think I should only be getting 1 code. The code that refers to the pass. side sensor missing. It could be that maybe the 02 sensor I put in is bad? I've got a couple others laying around, maybe I'll just swap another one in and see if it eliminates 1 of the codes.

Fink

How many threads are you going to make about this? Like seriously, its not rocket science on what you need to do.


Not trying to be a dick, just annoyed by all the threads your making over this small issue.

mustang99v6

Actually Fink, I have had different issues & questions. I had a quick needed question on 02 sensors in general and that was 1 thread. I asked them to delete it but they didn't. Then I had general questions on headers and that is it's own thread. Then this is a code question thread strictly pertaining to that. Related, but not the same issues. Sorry if I seem to have too many threads on it, but they are all different topics.

On the rocket science part, yes I know what I "need" to do. Get 02 extenders boom. Not exactly. I'm trying to understand these codes so that I can send all the correct info over to the tuner. I don't have a way to data log right now, so all I can go off of is what my car is telling me(or not telling). That combined with the knowledge I get from this board allows me to make wise decisions about my car. I'm not gonna just take one internet opinion that I read somewhere and accept it to gospel. I test things out and get to the bottom of them, then I report my findings so others can benefit.