PNRD4321 (I thnk) problem

[awolfinsheepsclothes]

hi everyone
Started the car after work, pulled forward 10ft or so and left the car running in park while I filled the washer bottle and when I went to set of put it in d and the gear display was all red with no proper drive but reverse !
Turned it of to reset and it was ok then and worked ok on the journey home.
I'll check the oil level tomorrow and code read it
The mileage is 135k so may be due to nap it!
I had quick look in transmission section for the f125 symptoms and the only one I've found was Richierich37 and he doesn't continue his post after nov 2012
The kick down switch was turned of until 122k so I was hoping it had a easy life until me
The car only just started this morning due to drained battery could the low voltage have caused this?
Any advice cheers Dave