A Safe-T-Alert alarm uses a small number of light and sound patterns, and each one means something different. Some mean gas, some mean the alarm itself has a problem, and one means the alarm has reached the end of its life and needs replacing. This guide uses MTI's own list of signals from the Safe-T-Alert FAQ.
If the alarm is sounding a gas or CO pattern, treat it as real. Never ignore a sounding alarm: get everyone out into fresh air and ventilate the RV. MTI's alarm mute button silences the horn while you ventilate, and the rapid-recovery sensor will set the alarm off again if dangerous levels of gas are still present.
What each Safe-T-Alert signal means
| Condition | Sound | Light |
|---|---|---|
| Normal | None | Steady green |
| CO alarm | 4 beeps, then 5 seconds off, repeated | Steady red |
| Propane alarm | Constant | Flashing red |
| Alarm malfunction | One beep every 25 seconds | Alternating red and green |
| End of life | One beep every 25 to 30 seconds | Red, red, green, green flashing |
| Warm-up after power is applied | None | Flashing green: up to 10 minutes on CO alarms, up to 2 minutes on propane alarms |
MTI adds that if the lights are blinking on an alarm wired into your RV, the RV battery may be run down, so charge it.
Chirping every 25 to 30 seconds
A single beep every 25 to 30 seconds with the red-red-green-green light pattern is the end-of-life signal. MTI says you can push the reset button to silence it for 3 days, and the alarm must be replaced within 30 days. This is not a fault you can repair: the UL and CSA carbon monoxide standards and the UL 1484 propane standard require these alarms to be designed to stop service when their operational life is reached. See when to replace an RV CO and propane alarm.
A single beep every 25 seconds with alternating red and green is a malfunction. If the malfunction signal will not reset, MTI's troubleshooting guide says to check the battery voltage first; if the voltage is good and it still will not reset, contact MTI customer service. (MTI's troubleshooting table describes this signal as a beep every 15 seconds, its signal chart as every 25 seconds.)
No green light at all
MTI's troubleshooting list for a green light that is off:
- Bad wire connection
- Reversed wiring
- Main power off
- Missing or blown fuse
- Then contact MTI customer service
Because these alarms run on the coach's 12 V system, a battery disconnect switch left off is the first thing to check.
How to test a Safe-T-Alert alarm
MTI's testing steps are the same in outline for CO, propane and combination alarms:
- Check the date code. Replace the alarm if the date has expired. MTI says to replace propane and CO alarms that are over 5 years old.
- Press and hold the TEST button for 1 second. The green light should turn red. On CO and combination alarms the horn beeps 4 times, and on combination alarms the gas light also blinks red. The TEST button checks the electronics only, not the sensor.
- Test the CO sensor with a can of Safe-T-Alert CO test gas, which checks the 400 ppm calibration point using the test chamber supplied with the can. MTI is clear: do not try to generate CO to test the alarm.
- Test the propane sensor with propane or butane gas. MTI notes it may take up to 10 seconds for the alarm to sound.
If an alarm does not test properly, MTI says to return it immediately for repair or replacement.
Replacing a beeping alarm
If yours is at end of life, find the matching current model in our Safe-T-Alert replacement chart, or check sizes in the size guide. Common swaps: an old 30-442 propane alarm to the 35-742 CO + propane alarm, a 20 Series to the 25-741 Mini, or most alarms with an odd cutout to the 85 Series universal alarm with trim ring. For general propane-alarm troubleshooting across brands, see RV propane detector keeps beeping?
Frequently asked questions
Why does my Safe-T-Alert beep 4 times and pause?
Four beeps followed by 5 seconds off, with a steady red light, is MTI's CO alarm pattern. Get out and ventilate.
Why does my Safe-T-Alert sound constantly with a flashing red light?
That is the propane alarm pattern. Get everyone out, ventilate, and have the gas system checked before using it again.
Can I reset the end-of-life chirp?
For 3 days only, using the reset button. MTI says to replace the alarm within 30 days.
Does the TEST button prove the sensor works?
No. MTI says the TEST button checks the electrical functions. Use CO test gas for the CO sensor and propane or butane for the gas sensor.
Every Safe-T-Alert alarm we sell ships from our warehouse in Upland, California. Not sure which one replaces yours? Send us a photo of the old alarm and its label before you order and we will match it. Browse the full Safe-T-Alert range.