Read these carefully
Safety-critical light guides
Some lights should not be ignored. This hub groups warning lights connected to alarms, carbon monoxide, vehicles, batteries, power, appliances, and medical devices.
Router Blinking Orange Light
A blinking orange light on a router usually means the router is starting up, trying to connect to the internet, updating firmware, or reporting a connection issue.
Router & Modem Lights · General
Router Solid Red Light
A solid red light on a router usually means the router has no internet connection, failed to connect to the modem, detected a service issue, or is showing a device-specific fault.
Router & Modem Lights · General
Netgear Orbi Purple Light
A purple or magenta light on a NETGEAR Orbi system commonly points to an internet connection issue, failed sync, or the router being unable to reach the internet.
Router & Modem Lights · NETGEAR Orbi
Smoke Alarm Blinking Red Light
A blinking red light on a smoke alarm can mean normal operation, a recent alarm event, low battery, hush mode, or a device-specific warning depending on the model.
Smoke Alarm Lights · General
Carbon Monoxide Detector Red Light
A red light on a carbon monoxide detector can indicate alarm, fault, memory, low battery, or end-of-life depending on the model. Treat any CO alarm as serious.
Carbon Monoxide Detector Lights · General
Check Engine Light Flashing
A flashing check engine light often indicates a serious engine misfire or condition that can damage the catalytic converter. It should be checked quickly.
Car Dashboard Lights · General
Xfinity Modem Blinking Orange Light
A blinking orange light on an Xfinity modem or gateway usually means the device is trying to connect, activate, update, or recover from a network connection problem.
Router & Modem Lights · Xfinity
Eero Red Light
A red light on an eero usually means the device is not connected to the internet or cannot reach the network correctly.
Router & Modem Lights · eero
First Alert Blinking Red Light
A blinking red light on a First Alert alarm can mean normal operation, alarm memory, an active alarm, low battery, or another model-specific condition.
Smoke Alarm Lights · First Alert
First Alert Green Light
A green light on a First Alert alarm often indicates power or normal operation, but the exact meaning depends on the model and whether the light is steady or blinking.
Smoke Alarm Lights · First Alert
Kidde Smoke Alarm Red Light
A red light on a Kidde smoke alarm can indicate normal status, alarm memory, active alarm, low battery, hush mode, or a model-specific warning.
Smoke Alarm Lights · Kidde
CO Detector End-of-Life Light
A CO detector end-of-life light means the alarm has reached the end of its sensor life and should be replaced, not ignored.
Carbon Monoxide Detector Lights · General
Battery Light on Dashboard
A battery light on the dashboard usually means the vehicle charging system is not working correctly, not simply that the battery is old.
Car Dashboard Lights · General
Oil Pressure Light
An oil pressure light can mean the engine does not have enough oil pressure. It should be treated as serious because continuing to drive can destroy the engine.
Car Dashboard Lights · General
Tire Pressure Light
A tire pressure light usually means one or more tires are underinflated, but a blinking TPMS light can indicate a sensor or system problem.
Car Dashboard Lights · General
Router Internet Light Red
A red internet light on a router usually means the router cannot reach the internet through the modem, gateway, ONT, or ISP connection.
Router & Modem Lights · General
Epson Printer All Lights Flashing
When all lights are flashing on an Epson printer, it often means the printer detected a serious error such as a jam, internal obstruction, or service condition.
Printer Lights · Epson
Airbag Light on Dashboard
An airbag light usually means the supplemental restraint system detected a fault and the airbags or seatbelt pretensioners may not work correctly in a crash.
Car Dashboard Lights · General
ABS Light on Dashboard
An ABS light usually means the anti-lock braking system has detected a fault. Normal braking may still work, but anti-lock braking may be disabled.
Car Dashboard Lights · General
Temperature Warning Light
A red temperature warning light usually means the engine is overheating or coolant temperature is too high. Continuing to drive can cause severe engine damage.
Car Dashboard Lights · General
Verizon Router Red Light
A red light on a Verizon router usually means the router has a connection problem, internet service issue, or router status warning depending on the model.
Router & Modem Lights · Verizon
AT&T Gateway Red Broadband Light
A red broadband light on an AT&T gateway usually means the gateway cannot establish or maintain its broadband connection.
Router & Modem Lights · AT&T
Smoke Alarm Yellow Light
A yellow light on a smoke alarm usually means attention is needed, such as low battery, fault, hush mode, end-of-life, or a model-specific maintenance condition.
Smoke Alarm Lights · General
Smoke Alarm Solid Green Light
A solid green light on a smoke alarm usually means the alarm has power or is operating normally, but the exact meaning depends on the model.
Smoke Alarm Lights · General
CO Detector Green Light
A green light on a carbon monoxide detector usually means the alarm has power or is operating normally, depending on the model.
Carbon Monoxide Detector Lights · General
Surge Protector Red Light
A red light on a surge protector can mean protected, grounded, fault, or warning depending on the label next to the light and the model.
Battery Charger Lights · General
Brake Warning Light
A red brake warning light can mean the parking brake is on, brake fluid is low, or the brake system has a fault that needs immediate attention.
Car Dashboard Lights · General
Traction Control Light
A traction control light can mean the system is actively helping during slippery conditions, turned off, or reporting a fault depending on whether it flashes or stays on.
Car Dashboard Lights · General
Medical Device Battery Light
A battery light on a home medical device usually means the device battery is low, charging, missing, not detected, or needs replacement depending on the device.
Medical Device Lights · General
CPAP Red Light
A red light on a CPAP machine usually means the device needs attention, such as power, humidifier, filter, mask leak, service, or a model-specific fault.
Medical Device Lights · General
When a light is more than a status signal
Some device lights are harmless setup or power indicators. Others can point to fire, carbon monoxide, electrical danger, overheating, vehicle safety issues, medical equipment warnings, or a device that should not be used until it is checked.
If a light is connected to smoke, fire, gas, carbon monoxide, brakes, oil pressure, overheating, batteries, medical equipment, or electrical damage, stop and follow official safety guidance first.
Do not delay emergency action
This site provides general information. It should never delay leaving a dangerous area, calling emergency services, contacting a qualified technician, or following the official manual for a safety device.