Testing with a multimeter lets you know the valve works. Turn off the furnace at the wall control. Take out the bolts in the service panel on the side of the furnace using a nut driver. Pull the wires off the gas valve terminals. Turn the test control on the multimeter to “mV,” which stands for millivolt. Click to see full answer. Besides, how many ohms should a gas valve read?Set the multimeter to the ohms-times-10 setting. Read the gauge. The reading should change from infinity to approximately 1,300 ohms, plus or minus 150 ohms, when the probes contact. If the reading shows infinity or deviates too much from the 1,300 reading, it indicates a defective valve solenoid coil.Also, what causes a gas valve to go bad? There are several reasons this valve may stop working properly. The valve itself may have simply worn out or may be damaged due to basement seepage or submersion. Alternately, one of the electronic gas ignition components or a glitch in the safety circuit may be to blame. Thereof, how do you test a gas valve for continuity? How to Check the Furnace Gas Valve With a Multimeter Turn off the furnace at the wall control. Take out the bolts in the service panel on the side of the furnace using a nut driver. Pull the wires off the gas valve terminals. Turn the test control on the multimeter to “mV,” which stands for millivolt. How do you test a thermocouple? Steps Locate the pilot light controls on the gas valve. Turn the pilot light on for 30 seconds. Release the button to see if the pilot light goes out. Turn off the gas supply to test the thermocouple again. Count to 20 and wait for the pilot light to go out. Listen for clicking near the gas valve.