It happened again yesterday and I think I might have figured it out. Once again it went into limp mode where the engine wouldn't rev above 2500rpms and the transmission shifted really erratic and hard BUT, right before it happened I was traveling very slow up a rather steep hill. At the top of the hill was an intersection with a stoplight that doesn't stay green for too long so the traffic was moving slow. Anyways, on the hill I felt the transmission shift a little off and then bam - limp mode. Come to think of it, when it happened earlier in the week I was also on a hill except I was traveling down it.
So my theory is that I'm low on transmission fluid. When I'm on a steep hill the sump goes dry and the ECU and/or TCU realizes this so it forces the car into limp mode to prevent further damage.
When I turn the car off for 15+ minutes the fluid returns to the sump and when I restart the engine everything is good to go.
I'm bringing the car back to the dealer on Monday for a scheduled appointment where they are going to check the transmission fluid level. If the level is fine then I'm at a loss - Although a healthy transmission is never a bad thing
. If the fluid level is low then they I'll have then fill it up but then the even bigger question is why is it low? There are no external leaks.
It's a catch 22. Do I want to find out that my transmission is failing so I can solve the limp mode problem or do I hope the transmission is fine and keep dealing with this mysterious problem?
Question - if the transmission fluid was ever low enough to cause problems, wouldn't it through a SES (CEL) light on the dash?