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Q: Tranny troubles

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I have a 2009 gmc sierra 1500. 4.8 liter V8. Automatic. The other day the truck started downshifting on its own. My buddy got his code reader and got P2771 icy conditions as the code. Checked the tranny fluid it was very low found out it's leaking from the bell housing. I played with the transfer case moving it 4l 4h and 2 and got the code to clear that way. Took it for a spin and it shifted from 1st to 2nd fine ( it was running high rpms before and shifting back down) 2nd to 3rd the rpms jumped but it shifted. It would not shift from there. We looked for corroded wires but couldn't tell if any were bad. Not sure how to proceed from here or what the issue is. Can you offer advice?

My car has 92000 miles.
My car has an automatic transmission.

You need to have the transmission leak from the bell housing fixed. The fluid leaking is causing the transmission shift problem. The trouble code P2271 indicates that the O2 sensor after the converter shorted rich. This may happen if transmission fluid got on it and caused it short out. I suggest having your car looked at by a certified technician, like one from YourMechanic, they will be able to pinpoint the fluid leak and address the issue from there.

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