Q: I have a 2009 VW Jetta S 2.5L. Why does my car turns on but then it turns off after driving it for a bit/while?

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I was going to the store, that is like 5 mins. away from my house, turn the car off, went inside the store and came out after like 15 mins. turn the car on and after being for about a min or two. it shut down by it self. I try to turn it back on and it sounded like it was going to start but it didn't. I tried one more time and this time it didn't do anything. I replace the battery less than a month ago. since my car didn't turn on, I left it there in the parking lot, came back like 3-4 hrs later. turn the car on and it did turned on. I drove it to a near by O'reily auto parts store and had them scan my car. and they came up with some codes that need to be fix. the codes were as follow: P0864 , P0070 , P0721 , P0734 , P0811. one or two codes belong to the transmission and the transmission was replace like one week ago. so am not sure if am supposed to clear those codes after the transmission being replace. on top of that my key gets stuck in the ignition.

My car has 118000 miles.
My car has an automatic transmission.

These are the following definitions for the codes you’ve received:

  • P0864 - Transmission control module (TCM) communication circuit -range/performance problem
  • P0070 - Ambient Air Temperature Sensor - (possibly shorted but most likely not related)
  • P0734 - Gear 4 Incorrect Ratio Code (3-4 shifting improperly)
  • P0721 - VSS - Vehicle Speed Sensor
  • P0811 - Excessive Clutch Slippage

With multiple transmission faults after a transmission replacement, either the speed sensor itself was damaged during the transmission replacement or the wiring to it may be loose/damaged. Also, a bad transmission control module can be the problem. Sometimes, the trans control module is specific to the transmission and requires replacement along with the transmission in order to function properly. I would have the codes cleared to see which (if any) codes come back. From there, they can pinpoint which problems are still causing the car trouble.

As for the key getting stuck in the ignition, this may be due to the shifter cable being improperly adjusted after the transmission replacement and affecting the shifter interlock between the brake pedal, ignition, and shifter. To have all of these problems checked, a certified professional, such as one from YourMechanic, can give your car a comprehensive inspection and let you know how to best proceed with any adjustments or repairs.

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