Check Engine Light

[Spud]

The engine light on my 92 525i comes on when I decent from altitude >6000', but goes off after a short while when at <1000'.
When I checked the codes it returned an oxygen sensor fault, but I changed that a few months ago.
Is it possible that extended running at low speed and at altitude when descending can cause a fault? The cars seemed to run fine otherwise, but
I'd be interested to know what's causing it.

Any ideas?

Thanks

[632 Regal]

reboot the computer and check the code again when it happens, could be a fluke.