Transmission hard shifting as it goes up through the gears (real bad. 1 to 2) Dealer says knock senser.
How would knock sensor affect transmission shifting?
No matter what, if you have not exceeded the mileage, should be covered under your power train warranty.
Knock Sensor - Repair or Replace
A failed Knock Sensor will often have no noticeable symptoms beyond a check engine light or engine ping or knock, but it does cause your 2018 Toyota Tacoma to operate inefficiently and produce higher emissions. Our technicians have access to manufacturer-approved repair processes and Toyota genuine parts.
Is the check engine light on? A bad knock sensor can cause the ignition timing to be off and the engine to run poorly. A badly running engine might cause rough shifts but it seems to me there would be other symptoms. OTOH, you might need a fresh BS sensor. If the dealer us fixing it under warranty, go for it. If not, get a second opinion.
Knock sensor failure will cause drivability issues. When P0327 or P0328 knock sensor faults are set, the computer will go into fail-safe mode. Ignition timing will be in full retard and a loss of power will be noticeable, this can be misidentified as a transmission issue.
Engine sensors are only covered by the 3 year/36,000 mile basic warranty, not covered by the powertrain warranty.