Illustrative dataParked or on the road, one screen
Trailers in the yard report to the site gateway. On the road, a cellular gateway rides in the truck, so the readings keep coming between stops.
TemperatureWise for reefer trailers
Temperature monitoring for reefer trailers
Know when a reefer stops cooling, while the load is still safe. In Mississauga, TemperatureWise flagged a stopped reefer holding up to $125,000 of stock. The team got there before the safety line.
- Reefers parked as storage
- Food distribution fleets
- Producers with their own trucks
- Yards and docks
4 hoursfrom a parked reefer stopping to the TemperatureWise alert
4 hoursfrom the stop to the alert, at 10.9°F (-11.7°C)Mississauga, December 2025
Up to $125,000of frozen stock in that one trailerMississauga case study, estimate
4.1°F (2.3°C)still below the safety line when the team arrivedMississauga, December 2025
What you get
Four things TemperatureWise does for a reefer
Illustrative data
Illustrative dataIt sees a stopped unit in the first hours
Normal cycling stops and the line starts to climb. TemperatureWise watches how fast it is climbing, not just where it is, so the alert can come hours before a threshold.
Why the slope beats a threshold
Illustrative dataA record the shipper can ask for
Under the US transport rule, a shipper or receiver can ask the carrier to show the temperature was held. TemperatureWise keeps every reading, every 15 minutes.
Illustrative dataAlerts climb until someone answers
Email first, then a text, then a phone call. A holiday no-start reaches a person, not an empty yard.
Where it goes wrong
Five ways a reefer loses temperature
One is from our own failure data. Four follow from how reefers work, and each says what the log shows.
From the data
Flagged 4 hours after it stopped in Mississauga, December 2025, and reached before the safety line
A diesel reefer that stops and does not restart
On an automatic stop-start cycle, the engine shuts off when the box is cold and restarts when it warms. A weak battery, worn glow plugs or diesel that gels in deep cold can stop the restart, and cooling just stops.
- How fast
- Hours
- What the log shows
- Normal cycling ends and a straight climb begins
- How to tell
- No restart after a normal engine-off period
How it fails
A torn air chute leaves the back of the load warm
Cold air leaves the unit along a fabric chute on the ceiling and returns along the floor. A torn chute or a missing bulkhead lets the air fall short, so the nose stays cold and the tail runs warm.
- How fast
- Minutes to days
- What the log shows
- A nose sensor and a tail sensor disagree
- How much
- Often 10 to 20°F (6 to 11°C) nose to tail
How it fails
In a frigid North American winter, a stopped unit freezes a fresh load
Below freezing outside, a reefer carrying fresh product runs in heating mode to keep the load from freezing. If the unit stops, the load does not warm up. It falls toward the outdoor temperature.
- How fast
- Hours
- What the log shows
- A fresh load falling below its setpoint
- How to tell
- Only a low alarm catches it
How it fails
Multi-drop routes open the doors at every stop
A delivery route can run 10 to 40 stops, and every one lets warm air in. A box that recovers between stops is fine. One that ends each stop a little warmer is running out of margin.
- How fast
- Across one route
- What the log shows
- The box ratchets up, stop by stop
- How to tell
- It resets at the depot, then starts again
How it fails
An all-electric unit fades late in the route
A battery-electric unit has a fixed amount of energy per route. Heat, extra stops and a frigid winter all use it up faster, so the box holds less well near the end.
- How fast
- Late in each route
- What the log shows
- The temperature drifts up in the last part of the route
- How to tell
- It gets worse as routes get longer
A real failure, real numbers
A parked reefer stopped on Boxing Day, and TemperatureWise got the team there before the safety line
26 December 2025, step by step
- Normal cycling near 5°F (-15°C). Nobody on site for the holiday.
- The reefer stops during an automatic cycle and does not restart.
- TemperatureWise alerts the team, at 10.9°F (-11.7°C).
- The customer's team is on site. The trailer is at 13.5°F (-10.3°C), still below the 17.6°F (-8°C) safety line.
- The reading jumps to 19.8°F (-6.8°C) for under half an hour while the team works on the unit. Open doors or a defrost as the unit starts would both do this.
- The reefer runs again. A weak battery is confirmed as the cause.
- Back near the -0.4°F (-18°C) target, about an hour after the restart.
The alert gave the team hours to act while nobody was on site. They reached the trailer with the load still below the safety line. The full story and the exported readings are in the Mississauga case study.
Pricing and payback
One trailer costs $775 up front and $550 a year
One trailer, a sensor at the nose and one at the tail
| Item | Once | Per year |
|---|---|---|
| 2 LoRa sensors at $200 | $400 | |
| Gateway that rides in the truck | $250 | |
| Cellular connection | $125 | $50 |
| Monitoring, 2 sensors at $250 | $500 | |
| Total | $775 | $550 |
Two sensors catch a nose-to-tail split that one would miss. A trailer that only parks at a site with a gateway needs no gateway of its own. Price list of 1 September 2026.
One caught no-start was worth 227 times the yearly fee
The Mississauga reefer held up to $125,000 of frozen stock. The yearly fee for one trailer is $550.
Multiple = the stock in the trailer ÷ the $550 yearly fee. The one-time $775 is left out, as on the TemperatureWise calculator. The stock value is the case study's upper estimate.
Want a detailed calculation for your own site? The full calculator on the TemperatureWise page takes your rooms, sensors and connection.
Open the full calculatorHow it works
Three steps, and the trailer keeps working
We plan it from your fleet and yard
TemperatureWise marks where each sensor goes in the trailer and where the gateways sit.
You fit the sensors and the gateway
Sensors go at the nose and the tail of the load space. The gateway rides in the truck, or sits at the yard for parked trailers.
It learns each trailer in the first week
TemperatureWise learns each unit's normal cycling and defrosts, so a normal defrost is not an alarm.
LoRa radio from the sensor to the gateway, cellular from the gateway out.
Every 15 minutesReadings kept indefinitely
Rated to -40°F (-40°C)Battery lasts 5 to 8 years
Temperature and humidityFrom one sensor
The rules
What US and Canadian transport rules ask of a reefer
US · 21 CFR 1.908(e)
If the shipper or receiver asks, the carrier shows it held the temperature the shipper set. The carrier also pre-cools the trailer as the shipper specifies.
Read 21 CFR 1.908Canada · SFCR s. 72
A vehicle carrying food to or from a licensed establishment holds a temperature suited to the food, with instruments that record it where needed.
Read the Safe Food for Canadians RegulationsTemperatureWise produces the record from the trailer. The shipper's specification and the sign-off stay with you.
Common questions
How often should I check the reefer temperature?
Every 15 minutes, if TemperatureWise is doing the checking: that is 96 readings a day, in the yard or on the road. By hand, a parked reefer can go unchecked over a holiday, which is when the Mississauga unit stopped.
Can TemperatureWise monitor a reefer on the road?
Yes. A cellular gateway rides in the truck and sends the readings out as the trailer moves, so alerts reach you between stops. Trailers that only park can report to a gateway at the yard instead.
How many sensors does a reefer trailer need?
Two: one at the nose and one at the tail. A torn air chute or a missing bulkhead can leave the tail 10 to 20°F (6 to 11°C) warmer than the nose, and a single sensor in the middle would miss it.
How much does reefer temperature monitoring cost?
About $775 up front and $550 a year for one trailer with two TemperatureWise sensors and a cellular gateway in the truck. Monitoring is $250 per sensor per year, and the cellular connection adds $50 a year.
Does TemperatureWise read the reefer unit's own controller?
No. TemperatureWise does not read the unit's controller, its alarm codes or its fuel level. It measures the load space on its own sensors, which is why it keeps reporting when the unit itself has stopped.
Proof
Case studies at a glance
- Philadelphia · April 2025$150,000freezer, 53 hours of warningA failed defrost timer, fixed in one visit. $0 lost.Read the case study
- Philadelphia · June to August 2025$450,000freezer, 27 days of warningTime to find old parts and move the stock to a reefer first.Read the case study
- Mississauga · December 2025$125,000reefer, flagged 4 hours after it stoppedReached before the safety line. Stock value estimated.Read the case study
See what your coldest room has been doing
Send us 30 days of readings from one room, or let us put a sensor in it. We will show you what it was doing before anyone noticed. No purchase needed.