If your ring door sensor says open when closed, test the original magnet before resetting or replacing anything.
A closed reading with the magnet held directly beside the sensor points to mounting geometry; no change points toward power, connection, or failed hardware.
That split can save you from buying a new sensor when a small alignment correction is enough.
Disarm Ring Alarm before touching the sensor, and keep the Ring app open so you can watch its state.
Don’t arm the system again until opening and closing the door produces the right reading every time.
Ring door sensor says open when closed magnet test
The contact sensor has two parts: the sensor and a magnet. Ring explains that opening the door breaks their magnetic contact, which is what lets the alarm report an opening. A false-open reading therefore begins with the physical relationship between those two parts, not with the app.
If the original magnet can be removed without prying or damaging the mounting surface, bring it directly alongside the sensor while the alarm is disarmed. Use the same orientation shown by the existing installation. If the app changes to closed, the electronics can detect the magnet and the installed position is the better lead.
Skip the random refrigerator magnet. Its size and field may differ, so the result won’t tell you whether the Ring parts meet their own mounting limit.
When the magnet is glued down or screwed into trim, press the closed door gently toward the frame and watch the app. A reading that flickers between open and closed as the gap narrows still points to alignment, a loose mount, or door movement. Stop if pushing the door could damage the latch or trim.
“When the door is closed they’re still registering as opened.” — a Ring owner describing the same symptom
That report identifies a symptom, not a cause. Your magnet response is the evidence that decides which branch to follow.
Measure the gap for your sensor generation
Close the door normally and measure the shortest distance between the sensor and magnet. Ring’s current positioning instructions set different limits: a 2nd Gen Contact Sensor must be no more than 2.5 cm, or 1 inch, from its magnet; a 1st Gen sensor must be no more than 1.25 cm, or half an inch, away.
For a 1st Gen unit, align the side notches too. Being inside the distance limit isn’t enough if the marked sensing areas pass each other at the wrong height.
Watch the gap while you close the door slowly. Weather stripping can push the door away from the frame, loose hinges can let it drop, and decorative molding can leave the two parts at different heights. Ring allows the sensor and magnet to meet at a right angle on a recessed frame, so matching faces aren’t required; reliable proximity is.
Metal doors and aluminum frames may interfere with the sensor’s signal. Test the position before making any new screw holes or committing fresh adhesive.
A Ring Contact Sensor Riser is a geometry fix, not a general upgrade. It lifts the sensor and its magnet together, which is what you want when the two closed surfaces sit at different levels. A Slim Magnet addresses a narrow mounting surface instead.
Neither accessory repairs an unresponsive sensor or a poor Z-Wave connection. Buy one only when the direct magnet test works and the installed geometry fails.
The five-foot move separates mounting from radio trouble
A sensor that reacts to the magnet but falls offline, appears unresponsive, or shows a poor signal has a different problem. Remove it from the mount as its instructions allow and take it within 5 feet of the Ring Alarm Base Station. Ring uses that distance in its Contact Sensor troubleshooting sequence.
Keep the original magnet with it and repeat the open-close test near the Base Station. If the state becomes reliable there, the sensor hardware and magnet can work together. The installed location, Base Station position, or Z-Wave path is now the useful lead.
That result is not a reason to order a new sensor.
Ring suggests moving the Base Station toward a more central location or considering a Ring Alarm Range Extender when the nearby test improves the connection. Choose between those only after returning the sensor to the door and confirming that distance, rather than alignment, makes the failure return.
If the sensor shows no light and doesn’t respond, reseat its batteries for a few seconds, then use the model’s specified replacement batteries if necessary. A working light doesn’t prove the mounting is correct, but no power prevents every other test from meaning anything.
This one-variable method is the same discipline used in the smart home troubleshooting guide: change one layer, record the result, and resist combining a reset, battery swap, and relocation into one unknowable attempt.
Reset last, then replace only the failed part
Use Retry Connection in the Ring app after the physical and five-foot tests. The current path is Alarm, Connected Devices, your Contact Sensor, Device Settings, Advanced Options, then Retry Connection. Follow the prompts and test both an open and a closed door state afterward.
Factory reset comes after that. Ring warns that a reset removes device settings such as chirps and volume adjustments, and the sensor must be added back to the app. The button sequence differs between 1st and 2nd Gen models, so follow the generation-specific steps on Ring’s support page rather than a generic video.
A sensor still stuck on open beside its original magnet, within 5 feet of the Base Station, after fresh power and a correct reconnect has earned a replacement decision. If it works off the door but fails only when mounted, replace or reposition the magnet, correct the height, or use the model-compatible mounting accessory instead.
Don’t let one bad reading weaken the rest of the alarm plan. Keep that opening out of armed coverage until the app reports each open-close cycle correctly, and contact Ring Support if the model identity or reset response remains unclear.
If the repair requires drilling into unfamiliar trim, the home installation guide shows how to identify the surface before choosing a fastener. The contact sensor itself is low voltage, but hidden wiring and brittle trim still deserve a deliberate stop.
Disarm the alarm now and run the original-magnet test once. Record “closes beside sensor” or “stays open beside sensor”; that single note tells you whether to measure the mount or troubleshoot the device.
Bolt & Bulb covers what goes wrong after the unboxing: devices that drop off Wi-Fi, dimmers that flicker with LED bulbs, locks that will not fit a rental door. The site draws on manufacturer documentation, platform support pages and release notes, and attributed owner reports in public forums.