So I just pulled up your logs. My initial takeaway is that as soon as your main throttle position sensor loses voltage, the sub sensor voltage spikes. Maybe this was just you actually mashing the throttle since it went into limp mode, so maybe this is nothing. The vertical line I marked is when it happens.

2023-09-15 19_35_51-Window.png

Here's a real zoomed in view of right where it happened. I guess if it were me I'd probably frustratedly mash the throttle so maybe that's what happened :-)

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Since the units here are V I would lean towards thinking that the main and sub sensor voltages are "raw". So it seems like something is killing that signal after 10 mins.

One thing to maybe check next, is to measure that conductor as close to the ECU as possible. Measure it when you know the car is NOT in limp mode, while datalogging, and see that your volt meter measurements match what the ECO sees. Then go drive it, let it go into limp, then take it back into your garage but don't turn it off. Presumably, the ECU will still be claiming to see 0V there. Check and see if it's actually 0V, or if you have the same behavior as you did when you checked it before limp mode on the volt meter. That'd at least help it isolate it to either something between the throttle and ECU, or something in the ECU itself (or another signal it's getting)

Or, maybe I just have no understanding of how the ECU works, and it's just pretending the sensor doesn't exist after it's seen something funky. That could make sense, if it's determined it can't trust data from that sensor it could just be shutting it off. In that case, try doing something to intentionally disconnect that line from the ECU, then reconnect it, all while it's running and datalogging. See if you see it go to 0V in the logs and stay there, or if it goes to 0V then comes back to life.

If you had an intermittent short/break I would expect to see that signal bounce between something "real" and 0V. Seeing it randomly jump to 0V and just stay there for the rest of the drive is strange.