Step-by-step fix
Step 1: Make sure the solenoid valve is the likely problem
- Wave your hand in front of the sensor and listen for a click from under the sink or inside the control box area.
- Check the easy causes first: fresh batteries if your faucet uses them, a plugged-in power connection if it is hardwired to a power pack, and fully open shutoff valves under the sink.
- If the sensor seems to react but water does not flow, keeps flowing, or only works intermittently, the solenoid valve is a strong suspect.
- Look under the sink and compare the old valve's hose connections, wire plug, and overall shape to the replacement part before you start.
If it works: You have ruled out simple power and shutoff issues and the replacement valve appears to match the old one.
If it doesn’t: If the faucet has no power, no sensor response, or the replacement does not match the original connections, solve that issue first before replacing the valve.
Stop if:- You see active leaking from cracked tubing, a split faucet body, or damaged wiring insulation.
- The shutoff valves will not turn or are already leaking around the stems.
- The replacement valve is clearly the wrong size or uses different connectors.
Step 2: Shut off water and prepare the work area
- Clear out the cabinet so you can work comfortably under the sink.
- Place a bucket or shallow pan under the valve area and keep towels nearby.
- Turn off the hot and cold shutoff valves under the sink by turning them clockwise until snug.
- Trigger the faucet once to relieve pressure and confirm the water supply is off.
- Disconnect the faucet's battery pack or power connector if it has one so the valve cannot cycle while you are working.
If it works: The water is off, pressure is relieved, and the faucet has no power while you work.
If it doesn’t: If water still runs when you trigger the faucet, the shutoff valves are not fully closing and need attention before you continue.
Stop if:- A shutoff valve will not close enough to stop the water.
- A shutoff or supply line starts leaking heavily when touched or turned.
Step 3: Remove the old solenoid valve
- Take a quick photo of the valve, hose routing, and wire connection so you can put everything back the same way.
- Disconnect the valve's electrical plug or control wire connector without pulling on the wires themselves.
- Loosen the water line connections at the valve. Keep the bucket under the work area because some water will drain out.
- Remove any mounting clip, bracket, or fastener holding the valve in place, then pull the old valve free.
- Check the hose ends and nearby screens or washers for debris while the valve is out.
If it works: The old valve is out and you know how the new one needs to be oriented and connected.
If it doesn’t: If a fitting is stuck, hold the opposite side with pliers or a second wrench so you do not twist the tubing or damage the faucet assembly.
Stop if:- A supply tube begins to kink, crack, or twist with the fitting.
- You find corrosion, broken connectors, or damaged hoses that will keep the new valve from sealing properly.
Step 4: Install the new valve in the same orientation
- Set the new valve in place in the same direction as the old one. If the body has a flow direction marking, point it the same way the old valve was installed.
- Reconnect any bracket or clip so the valve is supported and not hanging by the hoses.
- Thread the water connections on by hand first to avoid cross-threading, then snug them with a wrench. Do not overtighten.
- Reconnect the electrical plug firmly until it is fully seated.
- Make sure the hoses are not kinked, pinched, or rubbing sharply against the cabinet or sink frame.
If it works: The new valve is mounted securely, connected correctly, and the lines are routed cleanly.
If it doesn’t: If a fitting will not start by hand or the connector does not seat fully, back up and realign it before tightening anything further.
Stop if:- Any connection feels cross-threaded or will not tighten normally.
- The new valve cannot be mounted without stressing the hoses or wiring.
Step 5: Restore water and check for leaks
- Reconnect the battery pack or power connector.
- Slowly open the shutoff valves under the sink.
- Watch each valve connection closely for drips as pressure returns.
- Dry the fittings with a towel, then check again after a minute so even a small leak is easy to spot.
- If you see a minor drip at a threaded connection, shut the water back off and snug that connection slightly before retesting.
If it works: The valve and supply connections stay dry with the water back on.
If it doesn’t: If a drip continues after careful retightening, disconnect that joint and inspect the washer, seal, or connection alignment before trying again.
Stop if:- Water sprays, a fitting will not seal, or a hose connection appears damaged.
- The faucet begins leaking from inside the body or another hidden area unrelated to the valve swap.
Step 6: Test the faucet in real use
- Wave your hand in front of the sensor several times and confirm the faucet turns on and off normally.
- Let the water run for 20 to 30 seconds, then remove your hand and make sure the flow stops promptly.
- Test both short activations and longer hand-washing use so you know the valve responds consistently.
- Check under the sink one more time after a few cycles to make sure no slow leak has started.
If it works: The faucet responds normally, shuts off correctly, and stays dry under the sink during repeated use.
If it doesn’t: If the faucet still does not respond correctly, the problem may be with the sensor, control module, power supply, clogged aerator, or shutoff flow rather than the solenoid valve.
Stop if:- The faucet still runs continuously or will not run at all after the correct valve is installed and connected.
- You smell overheating electronics, see damaged wiring, or notice repeated leaking during testing.
Replacement Parts
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FAQ
How do I know the solenoid valve is bad and not the sensor?
If the faucet has power and the sensor seems to react but water will not start, will not stop, or works only off and on, the solenoid valve is a common cause. If there is no sensor response at all, check power, batteries, and the control side first.
Do I need to shut off both hot and cold water?
Yes. Many touchless faucets mix hot and cold through the faucet assembly, so shutting off both supplies helps prevent surprise water flow while you disconnect the valve.
Can I clean the old solenoid valve instead of replacing it?
Sometimes debris at the valve or screen can cause poor operation, so a quick inspection makes sense while it is apart. If the valve is sticking electrically or mechanically, replacement is usually the more reliable fix.
Should I use thread seal tape on the valve connections?
Only if that style of connection specifically uses threaded pipe sealing. Many faucet supply connections seal with washers or built-in gaskets, and tape will not fix a bad washer or a misaligned fitting.
What if the new valve fits physically but the plug is different?
Do not force it. A different connector usually means the valve is not the correct match for your faucet's control system. Use the old valve's connection style, size, and compatibility details to find the right replacement.