In order to perform a leak test you will need a bucket or bowl that can hold water and liquid dish soap. First create a mixture of 50% water and 50% dish soap. Then open your grill lid and ensure that all the control knobs are in the OFF position. Now turn on the gas at the propane tank, turning the knob counter-clockwise to fully open the valve. If you hear a rushing sound or smell gas, turn the knob clockwise turning off the gas. Tighten any leaking connections. If the leaking is detected at the nut and tightening does not stop the leak, then reinspect the propane tanks rubber seal. After inspecting the tank apply the soapy water mixture to the propane tank weld, connection nut, connection nut brass nipple, regulator connection to gas supply, entire length of gas hose, and tank valve. If there are any growing bubbles on the tank or hose this indicated a leak, note this may not detect large leaks however a large leak should be noticed by the rushing sound or the smell of gas. Tighten any leaking connections detected through the test and repeat the soapy water test until no leaks are detected. After completing the test turn off the gas until your are ready to use your grill. Wash off any soapy residue with cold water and a dry towel. Make sure to wait a minimum of 5 minutes until lighting your grill to ensure that there is no gas in the area. WARNING: DO NOT use the grill if the leaks cannot be stopped. Contact a qualified gas appliance repair service. CAUTION: Strong odors, colds, sinus congestion, etc. may prevent the detection of propane by smell. Use caution and common sense when testing for leaks.