Is there a special wire to use when making a custom O2 sensor harness?

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3gen5zr

New Member
Just curious...
i have done a obd0 to obd1 swap in my 89 prelude with a b20a.

The car originally was obd1 and is now obd2 with the new motor.
I have a ecu conversion harness for the new obd1 ecu.

I am having problems with code 41, (heater circuit)
The new motor has a single, 4 wire o2 sensor on the downpipe before the cat.

The engine harness is obd1, however the shock tower harness that leads into the car is still obd0, hence the conversion harness.

I have a o2 sensor plug that i soildered all four wires too inorder to wire it directly to the ecu. All four wires are taped up toegether and run from the 02 sensor through the fire wall and direcly to the ecu.

However, im still getting a code 41 , even with a brand new OEM 02 sensor.

Any recommendations?? any specific type of wire i should have used??
This problem is driving me nuts! Please help.
 
i did an extension on a o2 sensor in my car and i had a secondary heat curcuit failer i tryed everything it would go away untill i just got a new o2 sensor and left it hanging from the engine not screwed in yeah i know it sounds f-ucked up but the secondary after the cat just needs to be pluged in doesn't mater if it's in the exhaust
try it your CEL will not come back on i'm almost sure of it i've done it to three other cars now - 99 dx y8 header, 97 teg new header, 94 ex z6 header,
it has worked on all of these

all the secondary o2 does is read the air after the cat if it's not reading fuel then it's good so thus if it's not in the exhaust reading air/fuel then it's reading good clean air then hey it's good chillin out side but #### keep it dry !!!!#####
 
Hmm... i just have the one O2 sensor though :(

I have attempted to fix it a few times.. almost giving up as i just bought a brand new OEM o2 sensor..

i Just need it fixed so i can get it tuned! Its been like 8 months now.. its killing me lol

This is the one last thing from the major swap... i did auto to 5-speed and obd0-obd1 coversion.. but the dam o2 lol

i wanan get it tuned to get the power out of all the mods i did
 
In OBD1 ecu's there is no limp mode for a check engine light. You should be getting full power. Im pretty sure its only OBD2 that it would cause a problem.
 
Im running a PK3 ecu which is 90-91 prelude... after everything is all sorted out and no engine lights, then im running a PR4 ecu... i hooked up the other ecu as i was curious.. but still got an engine light with that one too

I have an a/f guage ( i know not the most accurate haha) but i got a light floating around on it.. so i know theres a single... but its running shady.. instead of one block.. it would be 3 blocks to 1 block and some of the blocks will be dim when they are moving around.

I did a single volt test.. im gettin a 0.5v.. even when i snap the throttle.. still 0.5v
 
whats limp mode??

thanks for the help guys... i really apprecialte this.. i hate these sorts of problems... all the complicated stuff was done! Just this on thing i need your help on!
 
Got the O2 sensor working, i was not getin any power through the 2 black heater wires when i was measuring voltage.

I have one of the black wires going to A6 (heater gnd) and then the other black wire i wired to A25 to supply the power when the ignition is turned

I have no more code 41, and no engine light :)

Does this connection sound right? or is there another power source for the 02 heater wire?
 
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