Q: Limp In mode on 1997 Dodge Grand Caravan

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My 97 Grand Caravan has about 190k on the speedometer. Never had a problem but the other day I was on the highway and tried to pass - RPM's went over 4000 and stayed there. Then Service Engine lite came on. The while the lite is on the vehicle will not shift up into drive and the RPMs stay high. Once the lite goes off the car is driveable. I am getting code 45 - something to do with "Turbo" and I don't have a turbo engine. However, every time I have tried to pass at speed the problem reoccurs.
(1) Answer
(1) Comments
It's time to visit a shop for a thorough diagnosis. Here is some background on the check engine light:

If you are going into limp mode, you have a significant problem that needs to be addressed.