Severity: Fix right away. Driving risks expensive damage or a breakdown.
The computer is getting no usable signal from the sensor that measures how fast the transmission input shaft is turning, so it cannot shift correctly.
Check the wiring and connector, clean the sensor, and replace it if it gives no signal.
The transmission may shift harshly or go into limp mode. Get it checked soon.
Avoid driving until it is checked — towing is the safer choice. The transmission may shift harshly or go into limp mode. Get it checked soon.
The most common causes are: Failed input speed sensor; Damaged wiring or connector; Metal debris on the sensor; Failing transmission computer. A scan tool and a visual check of the parts above is where a technician starts.
Check the wiring and connector, clean the sensor, and replace it if it gives no signal.
