Pacman123

Hi Guys,
I tried searching for the answer but I only get bits and pieces of information.

A few weeks ago I removed the rear housing of my gearbox and replaced a couple of bearings on the output shaft. I disconnected both O2 sensor connectors and moved the wiring out the way to make it easier. After I had finished, I put it all back together fine and proceeded to plug the O2 sensors back in.

Not looking, but feeling with my fingers, I plugged the sensors back in and started the car. Immediately I had a CEL come up on the dash. I checked the codes and it said both O2 sensors were dead. Thinking this was odd, I went back under the car and had a look. Turns out I was able to plug the ECU directly into itself and the O2 sensors into each other :S. I would not have thought that the two O2 connectors (directly next to each other) were the opposites of each other and even able to do that. I felt like such a moron.

I plugged the O2 sensors into the ECU harness properly this time, but now I have a constant P0135 code and CEL come up.

Question is, have I killed something in the ECU? or is it just unfortunate timing and the primary O2 sensor heater is dead? Has anyone else had this experience?

s2klariat

Did you reset light after switching back? Pull back up fuse for a couple of minutes and plug back in.

iamxpl

o2 sensor CEL will stay on until drive cycle is complete.

SlowzS2K

I have the same problem. ECU harness was connected to itself and the o2's were connected to each other. I corrected the connections and reset the ECU by disconnecting battery for 5 minutes or so and then letting it idle for about 10 min.

The CEL came back on right away and i have driven i dont know how many cycles and about 200 miles since

Symptoms are poor acceleration and VERY low idle, its even stalled a few times at a stop.

PS: New to the forums but not the S!

Pacman123

Thanks for the replies. Yea did all that unfortunately. Reset ecu, reset codes etc several times now. Unfortunately SlowzS2k post now sounds awfully similar.

I assumed it really wasn't good for the ecu, but seems rather stupid by Honda, although more stupid on my end too.
If I get a moment, i suppose i will test the heater circuit on the O2 sensor, and maybe try a new one to see if it fixes it. :S
unless anyone has any other ideas/ suggestions?

thanks all.

SlowzS2K

Yea im thinking that maybe the heater circuits in the o2's got damaged since they weren't meant to be plugged into each other but who knows. Im gonna order 2 new sensors from rock auto for a decent price and hope that the ECU didn't get F*%#d!

Iv learned my lesson not to do that again

Pacman123

Yea tell me about it :s who would have thought.
I am parking the S2k in the next couple of weeks due to respraying the front right fender and a couple of other small repairs.
I will test the O2 sensor and circuit at the same time when I get it up on some ramps.
I guess I will keep everyone updated.

eddiezzxdeeto

I did the same exact thing that both of you guys have done..... I was wondering if you guys were able to fix your problem. So far ive tested the voltage coming out of the ecm and I got 12v on primary heater and 3v on the secondary heater. When I have the car running the voltages dont go back and fourth like theyre supposed to. I checked my wires for any resistance but they had none. Im thinking its my ecu but I want to make sure thats what it is before I go out and buy one, thanks in advance.

Psyr

Any follow-ups here? I've been having O2 issues for quite some time and I would like to know if O2 sensors fixed this issue or if it is an ECU?

flanders

Connecting the two sensors to each other should not affect them at all, it's most likely an ecu problem.