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Q: Got a check engine code of 1899

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I drive a 1999 Jeep Grand Cherokee Laredo 4.0 6 cylinder and I recently got a check engine light code reguarding the park/ neutral switch . Everything seems fine it turns right on .reverse lights come on, and it turns on in neutral as well.. the only thing that I do notice is that when I'm driving I can see that my rmps go up high too 3k rpm then it shifts over too 3rd gear . I recently replaced a output speed sensor .. what could it possibly be?

My car has 150000 miles.
My car has an automatic transmission.

Hello. The symptoms you describe can be caused by a few different things. If you are showing code P1899, for a park / neutral safety switch that is stuck in gear then it may be possible that the switch needs to be replaced. The neutral safety switch directly effects the transmission behavior and can cause issues with the transmission if it has problems. In more serious cases it can even prevent the vehicle from starting if it goes out or experiences an issue. Another thing I would check is the vehicle’s transmission fluid. If the fluid is dirty, contaminated, or low it can cause the transmission to experience issues. Automatic transmission operate using fluid pressure, and any compromise in the fluid can negatively affect the transmission. A few other possibilities are the shift solenoids and the throttle position sensor. The computer uses these components to engage the transmission gears and shift points, and issues with them can sometimes cause symptoms similar to those you are experiencing. I would recommend having a professional technician, such as one from YourMechanic, come to your location to diagnose the cause of the transmission issues.

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