* Transmission slipping: The transmission may slip because it doesn't know how much torque to apply. This can manifest as the engine revving high without a corresponding increase in speed.
* Hard shifting: The transmission may shift harshly or at the wrong times, due to incorrect calculations of engine speed versus vehicle speed.
* Overheating: Slippage causes friction, leading to excessive heat buildup within the transmission.
* Limp mode: The transmission may enter a "limp mode" – a failsafe where it restricts gear selection to protect itself from further damage. This usually means it'll only operate in a few gears, often only 2nd or 3rd.
* No start or no reverse: In some cases, a faulty ISS can completely prevent the transmission from engaging, resulting in a no-start or no-reverse condition.
* Check Engine Light: The malfunctioning sensor will almost certainly illuminate the check engine light and will store diagnostic trouble codes (DTCs) retrievable with an OBD-II scanner. These codes are essential in diagnosing the issue.
* Erratic speedometer: While not directly related to transmission function, a faulty ISS often leads to inaccurate or intermittent speedometer readings because the speedometer relies on this sensor's input.
It's important to note that these symptoms aren't exclusive to a bad input speed sensor. Other transmission problems can cause similar issues. A proper diagnosis requires using an OBD-II scanner to retrieve diagnostic trouble codes and potentially further testing by a mechanic.
