Q: My 2014 VW jetta went into limp mode but I have no error codes.

Even though the check engine light is not on, a sensor can be at fault. It’s possible the throttle position sensor may not be sending proper readings to the engine control unit. Also, most cars today are "drive-by-wire". There is no mechanical connection from the gas pedal to the engine. When you press the gas pedal, sensors on the gas pedal tell the ecu how far you have pressed the gas pedal. The ecu then tells the throttle body motor how far to open the throttle. The sensors on the gas pedal or throttle body may be faulty. Also, other sensors like the crankshaft position sensor may be faulty and is not telling the ecu where each cylinder is in their revolutions. Since any of these can be at fault without setting fault codes, it’s best to have a certified technician look into why the engine will not rev. A simple code reader will not provide the information the proper scan tools can. Individual sensor values can be read with the proper scan device.