Transmission will not stay in gear when it is warmed up

2001 PONTIAC GRAND PRIX
200,000 MILES • 3.1L • 4 CYL • 2WD • AUTOMATIC
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RINDYHAUGAN
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When the car is cold started it runs and drives fine but as soon as it warms up it will no longer drive as it will slip out of gear.
Sep 15, 2019 at 3:28 PM
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JACOBANDNICKOLAS
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Welcome to 2CarPros.

Have you checked and confirmed the transmission fluid is clean and full? Also, has the check engine light turned on and stayed on with the engine running?

Have you ever serviced the transmission with a new filter? I have experienced issues similar to yours where dirt would fall away from the transmission filter while the engine was off. After driving or running the engine, dirt begins to be drawn back into the filter and block it causing the vehicle to basically go into neutral.

There are other things such as line pressure, so let me know what has been done so far.

Take care,
Joe
Sep 15, 2019 at 3:55 PM
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RINDYHAUGAN
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No service engine light was on. Haven't done anything with it yet as I haven't had time. I will be digging into it later today.
Sep 15, 2019 at 3:58 PM
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RINDYHAUGAN
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No service engine light was on. Haven't done anything with it yet as I haven't had time. I will be digging into it later today.
Sep 15, 2019 at 3:58 PM
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JACOBANDNICKOLAS
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Welcome back:

Let me know what you find or if you have other questions.

Take care,
Joe
Sep 15, 2019 at 7:54 PM
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RINDYHAUGAN
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Changed both the fluid and the filter. It continues to slip out of gear once warmed up. I guess the light was on, but when connected to a sensor it no codes appeared light was manually shut off (done by a family member).
Sep 18, 2019 at 11:07 PM
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JACOBANDNICKOLAS
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Welcome back:

If it is still slipping from gear, there should be a code. Was the scanner used able to read transmission codes? Also, by any chance was the code written down before it was deleted?

Joe
Sep 19, 2019 at 6:44 PM
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RINDYHAUGAN
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It was unable to show what code it was.
Sep 19, 2019 at 8:57 PM
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JACOBANDNICKOLAS
  • CAR REPAIR CONTRIBUTOR
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At this point, you may have to drive it carefully until the code resets. Since it still jumps out of gear, it should reset the code.

I wish I had an easier answer. There are many things that can cause this. Without the code, it becomes a guessing game and I don't want to have you buying parts only to not be correct. I'm sure you don't want to do that either. LOL

If you can, carefully drive it so as to not put yourself in danger and be easy on it so it doesn't cause additional damage. After that, see if the code returned.

Let me know.

Joe
Sep 20, 2019 at 9:28 PM