Wiring for post-cat oxygen sensor heater

[Actuary]

I’m trying to nail down the culprit for my bank 1, sensor 2 (post cat) code I’ve been getting.

My O2 sensor is new and the heaters seem to be working (the 2 heater lines are drawing 2.7 amps).

next I went to test connection on harness to DME, in case if line is burned or cut. My red wire is generating 12V when key is in position 1. I checked connections with multimeter for lines on harness connection and X60002 connector.

yellow seem to be good and rightfully giving signal with pin 16.

black is suppose to go to 22, but there is nothing there. I guess that’s expected since it’s ground?

brown is suppose to go to pin 7, but I get no signal. What’s interesting is brown on sensor side is getting connection to pin 5. I thought this should be empty per diagrams I’ve seen. The other interesting thing is red on sensor side is giving me a connection signal with 7.

does this sound right???

FYI - couple of years ago, I had a CSL airbox with flap installed by a shop. My reading of the wiring changes is just the addition of wires to pin 8 and 9 for flap sensor.

I appreciate any help on this. I’m in OC (Irvine California) if a local sees this and can lend a hand.

thanks!

[bigjae46]

I would check resistance of the wires end to end...that will tell you if you have a bad wire.


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[Actuary]

I would check resistance of the wires end to end...that will tell you if you have a bad wire.


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Thank but I believe that's what i did and that's how i was able to note the information on my initial post. My next step I feel is changing pin 5 to pin 7 on x60002. But before doing that I'm hoping someone in the community can help confirm or provide further guidance.

Is it okay that the brown heater wire on the O2 sensor goes to pin 5 of X60002?

[bigjae46]

I guess what I don’t understand is why are you trying to move wires in the harness to get the O2 sensor to work.

If you’re getting 12v you didn’t resistance test the wires. Both ends have to be disconnected and you get a reading in ohms.

If the harness is good, it’s either the DME or the sensor. IIRC, the heater circuit is parallel for each O2 sensor. So you should get a resistance reading at the DME connector and the O2 plugged in.

First off...didn’t really explain what code you have.

You could be getting a faulty code because the system is out of spec. Clogged or damaged cats (primary and/or secondary) are a real possibility.


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[Actuary]

Thanks for the response. I'll try to provide more detail and hopefully clarify the issues i'm having.

Issue
My car is throwing a code relating to heater control circuit high (Bank 1 sensor 2). This is the OBD II code P0038 and "39 lambda sobdenhzg 1 nah kat" in INPA.

1st Attempt to resolution - test O2 Sensors and inspect lines
I tested the heaters on both post-cat sensors (bank 1 and 2). They both read the same resistance at 2.7-3.0 (i stated amps in my initial post but i believe the reading was ohms...i'll double check that). The lines also look good and both post-cat sensors are about a year old and less than 3k miles. So I wasn't surprised.

2nd Attempt - Inspect sensor lines on the harness side
The lines pass the visual inspection and next I went to confirm there are no cuts or burns underneath the harness. To do this I looked at the electric diagrams (B62102/B62202) and information on pins for O2 Sensors (X60002).
1) Check if 12V is passing through the red line/pin when ignition is in position 1. Correctly, both sensors read around 12V.
2) Next I went to check continuity on both ends of each wire; 1 end of harness goes to the O2 sensor and the other end goes to the DME (X60002). For the sensor that was working, I was able to successfully get continuity readings. This made me feel confident in what i was doing. When I moved on to the sensor that wasn't working and that triggered my fault codes, i observed weird things. when checking the continuity for the brown wire, that's suppose to be the brown wire going to pin 7 per the diagram, i go no continuity.....testing other pins, i was able to observe that pin 5 in X60002 was the one giving me continuity. This was odd since this is inconsistent with electric diagram in 2 folds; 1) continuity should have been observed under pin 7 per diagram and 2) there should be no wires in pin 5.

I tried the remaining 2 lines (black and yellow). Yellow is giving me continuity to pin 16, while black (i believe ground) is not giving me anything -> not sure if that's concerning

This where I'm at lost here 🤔