The O2s are exact factory (oem) replacements. I compared the old wiring adapters to the new ones.. they are the same.Originally Posted by Shnraines
The O2s are exact factory (oem) replacements. I compared the old wiring adapters to the new ones.. they are the same.
Well...
... here we are.
I replaced the PCM... and NO JOY. Still no closed-loop and os2 voltages stay stuck at 450ish mV.
I am out of ideas! Anyone have another path that I have not taken yet???
O2s might be no good, try another one
Already replaced with new ones...
I meant the new ones might be bad. Did you try 2 new sets?
Yes, 2 new sets... one set of Delphi and one set of Bosch....
Check grounds with test light
I have found cause and solution... I wanted to come and close the loop (...lol) so maybe someone else can benefit from this train-wreck.
I will try to annotate this in chronological steps... it might help someone. I sincerely hope it does.
THE SHORT VERSION is the LG adapters I bought were wired 180 degrees backwards... read the rest of the story.
From the beginning...
1. I got a repeating DTC for the passenger (b2s1) O2 sensor fail error. (DTC P0154)
A. I replace both O2s and decide the LG O2 adapters need replacing also (100,000 miles of use) (these are the adapters sold by LG that allow you to run the rear sensor type in the front sensor connector, longer and higher wattage are the reasons)
2. I install the new O2s and the passenger side adapter (not the driver side.. it looks fine)
3. Now the craziness starts ( I assume the adapters from LG cannot be wrong )
4. The Scan logs show the passenger O2 sits always at 5ish mV, the driver side switches normally. The car runs terrible.
A. I don't yet know that the missed-wired LG adapters are backwards.
5. I think I have new O2s, and adapters, what is wrong???
A. I go ahead and replace the passenger side adapter, hope for anything.
B. I don't know this yet... but the miss-wired LG adapter blows that sensor now.
6. Now nether passenger or driver O2s are showing any activity... they flatline at 450ish mV.
A. I unplug the sensors and I check wiring harness voltages... everything is normal... I see 12v where I think I will... 450mV where I think I will, the other wires are ground to Splice-block 122 and low signal to the PCM. They all check correctly.
7. I replace the O2s again... ($$$)
A. Nothing different
8. Different Forums advise me my PCM is bad...
A. I replace the PCM... nothing changes
9. Still at this point I do not know the miss-wired O2 adapter have been blowing myO2 sensors.
10. I think my factory wiring harness is crushed or bad... I buy all the wiring supplies needed to create my own harness, just for the OS2s.
11. While researching the pin-outs for the O2 sensors I notice the new adapters from LG do NOT match the old adapters (also from LG)
A. I get under the car and multi-meter all the O2 connections for ground and voltage.
B. I realize the new LG sensors are wrong ( see attached PIC, left after I re-pinned it, right the way I got it ). The adapters are 180 degrees backwards.
C. I am guessing now that the new adapters have been sending 12v into the sensors PCM High Signal wire... and blowing it. It is only suppose to ever get from 1 to 900ish mV.
12. I decide this (the LG adapters wired wrong) is my problem all along
A. I re-pin the new LG connectors to what I know is correct.
B. It still does not work... I guess correctly the current O2s have been blown.
C. I buy and install new O2s... FINALLY everything works correctly again...
D. Cars goes into Closed-loop when expected... switches correctly
This was a 6 week lesson in chasing my own tail... because I assumed anything from the vendor had to be correct...
LG-O2-Adapter.jpg
Last edited by [email protected]; 03-22-2022 at 11:21 AM.
That sucks, but the lesson is test, never assume. Glad you got it figured out
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