Helpmewithmycar

btw these are upstream sensors
Hey running into a issue with the g and can’t really fine out the problem so basically car has long tube headers with the 02 extension harness I zip tied the extenders to not hit the headers one of them got loose and melted and extension got burned up got new ones and new 02 sensors throw them on car still in limp mode sometimes won’t start and throws circuit high code put in 02 sensor to check there voltage bank 1 is at 5 v!! Lmbda is 1.999 bank 2 is steady 2.4 with 0.999 lmbda even so I unplugged the extender see if it was the issue and with out the extender still at 5 v constantly I turn off the car turn it on and bank 1 starts at 2.4 v and climbs till 5 v and stays there so not the 02 or extenders checked the fuse it’s fine grounds and it’s fine checked the ipdm box nothing seems out the ordinary checked the 02 connector as well nothing out of the ordinary any help??? Any suggestions please and thank you

SkysG37

Did you try swapping sensors and see if the issue follows the sensor?

Helpmewithmycar

Hey yea I even swapped the extenders same thing on bank 1 I even used my old 02 sensors and the voltage on bank 1 stays at 5 same thing plugs goes straight to limp mode
even with them not connected obd scanner still ready 5 volts without being plugged in

beefychicken

Might have shorted something in the main harness.

referring to the FSM wiring diagram it shows 4 signals for the upstream AF sensor.

pin 1 is a 2v ignition on signal.
pin 2 is the variable output signal to the ECU.
pin 3 is a 3v to 8v power source from the ECU for the heater circuit.
pin 4 is a shared ground.

maybe this will help you find the source of the 5v signal.