i have a 96 civic ex coupe with a 99 si b16 motor in it. for some weird reason my car is throwing a CEL p0141 for the secondary O2. everything is plugged up and i even changed out that O2 from my car into my bros 98 ex coupe and its not throwing a CEL in his car. NOTHING is cut from the harness by the way. i currently am running a 96 ex ecu right now because i still waiting on rywire's obd2a to obd2b harness to plug up the 99 si ecu. either way with or without that harness it shouldn't throw a light right? because i installed my bro's p72 ecu and its still throwing a CEL. BTW my friends told me that the wiring is different on how the engine harness is set up but i know that already and i just extended some of my harness off my old harness and everything plugs and play. well i am out of ideas except that it could be electrical or that i need to run the 99 si ecu for the light to go off...well help me out and lmk....

P0141 Secondary Heated Oxygen Sensor (Secondary HO2S) (Sensor 2) Heater Circuit Malfunction

 

bump....state ref is coming up and i need to fix this...thanks

 

bump....

 

bump

 

bump

 

So you have the code and everything. It looks like it is the heater circut. Have you done anything like throw on a header or messed with the cat? Might just be a ground wire.

Have you thrown a known good one in and see if you still get the CEL. If you do this we can start ruling out possibilities.

There is a resistance test for the heater circut. sorry I don't have any info as to the spec's. Also make sure you are getting voltage to the heater circut.

There are a couple to think about. I will say usually it is the 02 sensor.

 

just replace the o2 sensor with a known good one or a new one. 9 out of 10 times it is just the sensor

 

i did replace the old one with a good one from my bros car and its still throwing a light. i just got rywire's obd2a to obd2b and the lights still on.

 

secondary o2 sensor eh? well that sensor just lets you know that ur catalytic converter has gone bad or isnt functioning. since u said theres nothing wrong wit the sensor then its probably ur catalytic converter. are there any other engine codes u have besides this one? if so then ur car might be running rich which indeed might destroy the catalytic converter.. in this case replace the cat