On most modern vehicles, a bad torque converter illuminates the check engine light. The specific problem is then stored in the vehicle's onboard computer, and mechanics read it using a professional scanning tool. Vehicles manufactured after 1980 generally include these sensors. HowStuffWorks recommends using a speed-stall test for checking older torque converters without sensors.
The torque converter includes a pump, turbine and stator. Problems with any of these components can cause the vehicle to shudder on take-off or stopping. They may also cause the transmission to slip while the vehicle moves.
Damage to the torque converter seal often occurs due to overheating of the unit. Transmission fluid then leaks through the failed seal, causing the converter to stop working. Failure of the main transmission torque converter clutch results as the elements of the clutch lock together, often due to severe overloading of the vehicle or distortion of clutch components. Shock to the clutch leads to breakage and converter failure, according to CarsDirect.
If a vehicle with an automatic transmission has difficulty transferring power to the wheels, torque converter replacement or repair is necessary. A damaged torque converter has the potential to eventually shut off an engine. Acceleration problems when operating a vehicle at low speeds indicate an overworked torque converter needing replacement.