Drive with caution — fix soon.
This code means the transmission computer sees an input (turbine) speed sensor reading that's outside the expected range or doesn't make sense compared to other sensors. Common causes include a failing input speed sensor, wiring or connector faults, or low and dirty transmission fluid. Repairs typically involve replacing the sensor or fixing the wiring, and are usually less costly than internal transmission repairs.
$100 – $500
Varies by vehicle and root cause.
Short trips are usually okay, but don't ignore it. The faulty speed signal can cause harsh shifting or limp mode, which is hard on the transmission, so have it checked soon.
It's often a relatively affordable fix. Replacing the input speed sensor and any related wiring typically costs about $100 to $500, depending on how accessible the sensor is.
It's moderately serious. The car usually still drives, but the unreliable signal can lead to erratic shifting and limp mode, so it's best not to leave it for long.
The input (turbine) speed sensor measures how fast the transmission's input is spinning, which the computer compares to output speed to control shift timing and detect slipping, so a bad reading throws off the whole shift strategy.