On a lakewood heater qtv-22 the caution light comes on now after about 20 mins of use has never done that before?

The caution light on your Lakewood QTV-22 heater typically indicates a malfunction or overheating. After 20 minutes of use, it could be due to dust buildup, a blocked air intake, or a malfunctioning thermostat. Check for any obstructions and clean the heater thoroughly. If the issue persists, consider consulting the user manual or contacting customer support for further assistance.