If your barbecue grill runs on natural gas, the Water Column Pressure may need to be checked by a Certified Gas Fitter. If your barbecue grill runs on propane please follow these troubleshooting steps:
The hose and regulator on your barbecue grill has a safety feature known as QCC1. This feature will activate if it detects a sudden flow of gas. This feature can accidentally be activated if the propane cylinder valve is opened with the control knobs in the on position. To correct this, simply turn off the tank and the barbecue grill, and then disconnect the regulator from the tank. Reconnect the regulator to the tank then very slowly turn the tank back on. This will reset the regulator, and allow normal gas flow.
If this does not resolve the issue, there may be a leak in the system causing the QCC 1 feature to be activated. Follow the steps to perform a "leak test" to determine the source of the leak.