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Q: Wonky cruise control and rough idle on low gear D

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Just a little background, my car is giving me two codes. P0770 for shift solenoid e and a Low Emissions Efficiency. I drive my car regularly and take it on thousand mile trips every other week. The problem I'm having is that the cruise control is unreliable. Sometimes it will be on for hundreds of miles and other times it will flicker and turn off the whole ride. My mileage seems pretty good and the ride is very smooth. However, at red lights and stops the car vibrates a lot. It can be overwhelming at times. Regardless, the car itself runs really well and it has never stalled on me.

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

A: Hello. P0770 is the code for a lock up torq...

Hello. P0770 is the code for a lock up torque converter shift solenoid malfunction. The lock up torque converter shift solenoid controls the fluid pressure of the torque converter, and the rate and timing at which it locks up. This may be the reason behind your intermittent issue. However, similar symptoms can be caused by many things. The cruise control is tied into the engine management system so it may also be possible that a sensor or wire is also causing the issue. Low speed engine vibrations can be caused by many things. I would first try to determine if the vibration is engine, transmission, or chassis-related. A few causes for vibration are engine misfires, worn motor or transmission mounts, or worn suspension components or tires. If you would like have to have this checked, a certified professional from YourMechanic can come to your car’s location to diagnose the rough idle and cruise control problems.

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