When the thermostats, fuses, ignitor and flame sensor function correctly, they send a signal to the coils or solenoids attached to the top of the gas valve. These coils or solenoids open the valve and release the gas into the burner assembly. If the ignitor glows and does not ignite a flame after 90 seconds, one or more of the gas valve coils or solenoids have failed. If the ignitor still fails to ignite the flame after you replace the coils or solenoids, the gas valve may have failed, and you will need to call an appliance service technician to replace it.