ok here is the story. i been fighting the rear o2 sensor cel light for a while now. here is a little recap of what has been going on

2003 evolution 8.

2 years ago i got a perrin o2 sim. works/worked great.

i then got a tbe system and the o2 bung was welded in the wrong spot. so the o2 sensor was hitting the drive shaft. finally the black wire broke off. which i did not know happened till i spoke to someone and i was asked to look. sure enough it was that wire. so i re soldered it back together. once again everything was good. then a few weeks later the wire broke again. so i said screw it. ill wait till inspection to worry about it. well its inspection time and here i am.

i re welded a new bung in a new location.

so i tried to fix the wire again but i cant. its broke to close to the sensor to get a good solder on there.

so i got a new sensor which turns out the 03 to 06 rear o2 plugs are different. so i returned that one.

i then got a used sensor online and it did not have the plug on it. so i had to cut mine off and connect it to the o2 sensor. there is a blue, white, and 2 black wires.

i was not sure what black wire went where. so i put it together and i still got the code. i swapped the black wires and tried again. still got the code.

i then checked the perrin o2 sim. the light is blinking so that means it is working and that it is hooked up properly.

so now at this point i put the anti foulers in and tried again. still getting the cel. i have another working o2 sensor off a 2003 evo coming tomorrow to try out. but if this does not work what do i do??

im gonna try the new sensor tomorrow but i figured i would post up and see if i can get some more info.

i would like to know if there is a patch or something i can do so i can get the car to stop throughing the codes and so i can pass inspection. im going to a private station so i dont have to worry about loud exhaust and crap like that. i was just told to make sure i dont have a cel light on.

the code is P0141: Heated Oxygen Sensor Heater Circuit sensor 2.

 

update. my plug is a 4 wire flat plug. not the 4 wire square one.

 

bump

 

dan i would say with all the joints in the wires and the endless soldering
by the sound if it have taken there toll, its a sensitive electrical item and
any resistance caused by bad electrical joints even soldered joints will
give false readings and/or cause faults.
you really need to get a new sensor complete there not that expensive

 

thanks for the tip. makes sense. im just the type who tries all aspects before jumping the gun to a new part. i have a buddy with a 03 evo as well and his works. we are going to try that. if that fixes the issue then i am buying a new one. but i would hate to buy a new one and find out i had another issue.. catch what im saying?

 

yes try a friends is a good call

 

i really hate my life some times. my friends o2 would not come out of the bung for anything. we tried and tried for ever. so instead of braking it and owing him a new one i decided to call it a day......

i then called another friend with a evo and this time it was an 05. and once again the plug was different. so now the 03,05,and 06 all have different plugs and the 03 has 2 part numbers depending on the month of the car..... AHAHAH. what a stupid project i have to go through. well i said screw everything. i ordered a brand new one 2 hours ago. it will be here in 3 to 5 business days. i will update the thread after its installed and see if the problem is fixed or not. but my luck tells me i have other issues. yummmmmmmy

 

i have a o2 sensor socket you could have borrowed. good luck with new one

 

Those sockets suck worse than a damn wrench sometimes. Nothing short of a torch to heat the f&^%er up was getting that bad boy out. But we didnt want to damage 2 sensors

 

so do i. but the type of exhaust it was had a little tube the o2 sensor was connected too. as i turned the sensor the tube wanted to bend as well.

 

remove the o2 sensor altogether. Search the "remove rear o2" thread in ECUFlash forums. I had a similar situation and right now my car throws ZERO CEL's and is imitating a rear heater so I will have no issues come inspection time.

 

hum. interesting. ok thanks sir. search time.

 

Yea I was telling Dan we could do this. Do we have a way for the Heater circuit to get to a ready mode. I know you can trick it with resistors to keep the CEL off but will it go ready when they put it on the scanner

 

i just read a thread about this. it will eliminate the code but it will not allow the ready tests pass when pluged in for emissions which wont let me pass inspection.

 

Scanner shows readiness tests are complete for me atleast =).

ps. its coding on top of the resister mod.