You have PO731 1st gear shift ratio incorrect as well?
You have nothing to worry about then. My car has had that code for several years. I have brang it to two shops they said nothing is wrong with the tranny at all.
See get this, the code only comes in cold months Nov. - Mar. will happen once a week, and will only happen within the first mile of driving. It has never came on after 1 mile, nor has it ever come before Nov. and after March, also it has never come during the day, only like 7:00 or so when I got to school.
Ignore that code, I do and have no problems.
One shop said maybe the Transmission Range selector is messed up but they didnt want to replace it and then have the code come back.
As for the prices go somewhere it should be cheaper to replace that stuff, plus OEM parts cost more so that is why it is so high.