so I have an 09 Impala and I'm having strange issues all the sudden. Got a P303( cylinder 3 misfire) and a P0842???. I think it's tranny solenoid related but can't find good info...love left?

 

I've moved your question to it's own thread in the Impala section where it belongs. Post your vehicle info please. (engine/miles)


Start with the basics. Inspect your spark plugs+wires, and verify good spark. Try swapping injectors. Then move on to things like cylinder compression testing.

It is indeed for the transmission.
https://www.obd-codes.com/p0842
You need to post how many miles the car has.
Is the fluid full? Have you been servicing the transmission regularly? Changed the filter?