Just thought I'd add my 2 bob's worth.
Mine was doing this as well.
Brought a brand new battery today, drove 20 miles or so, stopped the car for a few hours, came back to it and the trip computer hasn't reset. Drove home again. Car's been stood still since 7:30pm, just been out to it and the trip still hasn't reset.
Beforehand it'd reset if the engine was off for more than 10 minutes.
I'll see for definite in the morning, but I'm pretty sure the problem is resolved.
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