This is my first post so let me first start by saying HI! I got this 2004 TL sand have little background on it of what work has been done to it. I am chasing an error code which is the B2S2 Heater Circuit Malfunction and I am leaning toward an issue with the ECU and hoping someone can give me a hand. Yes I have search and searched.

What I have done:
1. bought a new sensor
2. swapped sensor with B1S2 which I know is good
3. built a test harness to connect B2S2 into B2S1 wiring harness -
4. used test harness to connect B2S1 into B2S2 wiring

this has all pointed to it is the wiring on B2S2 over and over as the code follows the wiring. now the wiring was hacked up and a new connector was put on it so that did not surprise me. So I checked connectivity on all wires and it was good, so no grounding out from what I can see. I also checked the voltage between Bank 1 harness and Bank 2 harness and this is where the issue is. On Wire 1 for Sensor 2 the voltage fluctates. It does not do that in Sensor 2...it is a hard number. This tells me it is not switching properly. I cut the wire at the ECU and ran a fresh wire all the around and nothing changed. Now I do not know where the Green/Yellow wire goes ( Schematic says "J") but I am guessing that is a grounding switch.

Bank 1 Sensor 2 wiring
1. Green
2. Green/Black
3. Black/White
4. White/Black

Bank 2 Sensor 2 wiring
1. White (B18) 14VG/4V
2. Green/Yellow (J - not sure really where this goes) 14VG
3. Green/Red (E8) 14VP
4. White/Black (24P Jumper box) 14VG


thoguhts??

 

Anyone?

 

First, B1S2 and B2S2 are both downstream (post-cat) sensors. They should not be switching if your cat is working properly.

I am not sure what 02 code means.

Is there a P0XXX code?

Can you provide a diagram of your modified wiring?

 

wanted to circle back for anyone in the future reading this. the ECU was determined dead ( main processor). There is also another issue that is being pointed to which is weak AF signal at the fuse box under the dash. The dealer wanted to replace it but I am wondering/thinking it is a grounding issue. I will work on that next....