Quote:
Originally Posted by Scrippy
So I recently got a check engine light. Scanned with ISTA and it’s 272D (O2 sensor heater after cat bank 2). I swapped bank 1 & 2 post cat sensors and the issue stays with bank 2. I have all 4 new sensors sitting on the shelf. I even threw my (2) new post cat sensors in bank 2 and no change. My question is…..from DME on passenger side cowl how do the 4 wires get down to the sensor? Can the wires be replaced with engine in or am I hating life? I want to inspect the wires all the way point to point and find the issue. I have a screen shot of the INPA live voltages and you can see that bank 2 is 249mV lower than bank 1. Swapping sensors and trying my two new sensors yields roughly the same mV desparity. I have already replaced the exhaust collector ring gaskets on both sides. My old gaskets were only 2 years old and looked just fine. Does anyone know the wire path? Could this be a leak at the header gaskets? I don’t hear or perceive any exhaust leak but I’m open to ideas here. Thanks in advance!
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Here is a wiring schematic that you requested since nobody else provided you with one yet. The bank 2 post-cat O2 is a bit of the worst because it has two splices for the supply AND ground to the heater element.
I suspect wiring here. In order to actually verify this, you would need to load both circuits and determine what the voltage drop is if there is compromised wiring; ergo a bad splice. This points to bad wiring because the heater element should always be roughly the same for post-cat O2s because they're both on the same circuit. Hopefully this makes sense for you and you can take it from here to electrically test the circuit.
As an FYI, the e-box locations for those connectors I referenced--I would take them with a grain of salt and actually verify you have the right connector. For instance, X6021 and X6200. Also, I cannot determine where exactly those splices are.