Hey All,


I am stuck trying to find the root cause of this issue... check engine light came on; checked GAP IID and found the codes (P0151-1A Bank2, Sensor 1 circuit low voltage - general electrical failure - circuit resistance below threshold & P0051-00 circuit low ( bank 2, sensor 1)


I checked, via IID, the output voltage of the post catalytic sensors and bank 2 never gets to the ~4-5v that bank 1 does. ... bank 2 never gets to a closed loop condition ... the lambda wide range output fluctuates around 1.01 for bank1; but stays steady at 1.00 for bank 2... when warmed up i see output voltage from bank1 - sensor 2 at .555v however bank 2 - sensor 2 shows .0400v ... and the post catalytic on bank 1 shows 4.81 while bank 2 reports 0 ???


I have also checked the voltage at sensor 1 - bank 2 - connector harness: both RED (UHEGO A SIG) & YELLOW (UHEGO A GND) show voltage ??? red-sig=2.83v & yellow-gnd=2.47v (cold; engine not running; key on) ... WHITE-GREEN source shows steady 11.97v and the A-HTR wire shows 0v cold and .03v when running (note: i didnt leave running long cause it gets hot down there by the connector)


QUESTION: should both SIG & GND wires have voltage? or should one of them be closer to 5v ? I 'think' i may have a short somewhere .... but that connector goes straight into the ECM ??


what else should i be checking?

 

Forgot to mention that I did replace BOTH bank 2 sensors as well ...

any thoughts what do look at next folks? I am stumped.

 

Keep in mind each bank is a side and usually sensor 1 is upstream with sensor 2 downstream. And O2 sensors generate their own voltage when warmed up so to help the upstream are usually heated for cold starts. So for what you typed above, it makes no sense since you say bank 2 sensor 2 shows .04v then you say bank 2 post cat shows 0. You may have mixed up your banks and sensor numbers making it hard to make sense of this.

 

Thanks for the response ... I was trying to put as much info into the thread but admittedly may have confused things with the complete data dump ;-)

lets ignore the IID tool output for now ... i could use some help confirming the correct behavior of Sensor 1 (pre-Cat) Bank 2 (right side engine from drivers seat):
- Should both SIG and GND wires have voltage?

• red-sig=2.83v
• yellow-gnd=2.47v (cold; engine not running; key on) ...
• WHITE-GREEN source shows steady 11.97v
• A-HTR wire shows 0v cold and .03v when initially started

 

Here is the schematic....

 

Don't have time to digest all the info, but are you aware that bank 2 is the drivers side?

 

Really?? I went through multiple threads to confirm that Bank 2 starts with cylinder 2 which...as I understand it... is on the right side if you are in the front seat looking forward out the windshield? But now you have me second guessing myself??

 

 

Well darn ... that changes things ;-)

thanks for clarifying ... I’ll check the ‘other’ bank sensors and wiring now. Lol.

 

Just to close this one ... it was in fact the o2 Sensor on the Drivers (Right) side before the CAT and above the driveshaft ... i tried to get to the darn thing more then a few times but ultimately had to break down and have the shop replace it for me :-)

Thanks for the direction and confirmation of Banks Abran !!