I have a 1997 Nissan Altima GXE - Auto. 120K miles. Combo
city/highway. Average 75 miles round trip a session. This was the
primary vehicle until February of this year, when I bought a new
vehicle. The vehicle has been well maintained with regular oil changes,
tire rotations, and most scheduled services done at the appropriate
time. I was hoping to keep this vehicle as a second car as it is
mechicaly solid except for one issue.

The check engine light is on. The engine code is for the line pressure
solenoid. I have had three different shops look at this problem dealer,
independent, and a transmission shop.

None of them have been able to resolve the issue at this point.

The first time it was brought in the dealer stated it was not an issue
that would leave me stranded on the side of the road and cleared the
error code. The issue went away for a good period of time. Then would
come back on, but I noticed that it was weather specific, in that cold
weather would clear the error state after 100+ miles or so, then as the
weather warmed up the light would come back on.

This allowed the vehicle to pass state emissions. However when it came
time for the 2006 emissions the light did not go away during the winter
weather as often. I took it in to the shops they replaced the solenoid
and the light went off for 100+ miles, and then returned.

I have had two proposed thoughts by the shops,

1. Wiring Issue (Dealer $90/hr)
2. CPU (Transmission Shop - Passed to dealer who stated $1000-$1500 )
3. Independent ( Passed to Transmission Shop)
a. However, the independent shop has provided me with the most detail
about the problem, stating the line pressure is normal the sensor or
CPU is getting stuck at the reading even though the pressure drops back
down to a nominal level (It has been a while so this description is
getting a bit vague).

My questions are,

1. Anyone experience similar issues? What was your solution(s)?
2. Any other thoughts or recommendations?