o2 heater issues. I'm lost!

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Sep 11, 2024 | 09:53 AM

Tyler Dietzenbach

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o2 heater issues. I'm lost!

Posted about this a few days ago. I'm still having the same problem. My o2 sensor heaters for both sides keep throwing codes. I've ran several continuity tests and even built new grounds coming off the pcm. I have the big 3 upgrade as well. All grounds are solid and new. The car will periodically kick back into open loop, so I'm positive this is a real issue.

I have no other issues of any kind.

Has anyone encountered this? Bad pcm?

Sep 12, 2024 | 09:19 AM

Tyler Dietzenbach

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Just tested for continuity at the o2 pins and found no issues. Which i didn't think i would since both sides keep throwing the codes.

Sep 12, 2024 | 09:37 AM

ss1129

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Just because continuity is good, does not mean the wire can carry a load. Try using the hot and grounds isolated to power a bulb.

Sep 12, 2024 | 09:51 AM

Tyler Dietzenbach

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Quote:

Originally Posted by ss1129

Just because continuity is good, does not mean the wire can carry a load. Try using the hot and grounds isolated to power a bulb.

I get that but the o2 heaters are case ground. To my knowledge the high and low signals have nothing to do with it. And the data doesn't show any issues with frequency readings. they are always reading. I would also find it hard to believe that 2 wires "broke" at the same time as well.

From what I understand is that the o2s share two things with each other. The PCM and the PCM grounds. I already built new grounds off the pcm as well to eliminate this as a possibility.

The codes for both sides throw at the same time, every time.

But if my thoughts are incorrect, please educate me on this.

Sep 12, 2024 | 10:03 AM

ss1129

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Look at the schematic, do they both share a common for the positive. Also there is a sensor fuse at the fender, IDK if the 02 sensors use it, but its worth a shot.

Sep 12, 2024 | 10:37 AM

Tyler Dietzenbach

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From: Kentucky

Quote:

Originally Posted by ss1129

Look at the schematic, do they both share a common for the positive. Also there is a sensor fuse at the fender, IDK if the 02 sensors use it, but its worth a shot.

I see what you mean. Heres the schematic. They do share a 15a fuse and it says "underhood" but idk how to tell which one... so I will check all the 15s in the fuse box.
Apparently the share the pink wire too? The thing that gets me is that they read in HPT all the time with no issues. So idk how it could be the power but maybe?

Sep 12, 2024 | 10:49 AM

Tyler Dietzenbach

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I found the fuse. It is the engine sensor fuse. Which controls

MAF/HEATER CIRCUIT O2's/BRAKE SWITCH/SKIP SHIFT/REVERSE LOCKOUT.

Going to check that here shortly

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