Carrier mini split error code E5
Evaporator coil temperature sensor (T2) open or short circuit.
- TypeFault
- SystemTemperature sensor
- Can I fix it?Homeowner checks, then maybe a tech
- Applies toindoor display, classic two-character codes (38MHRB, 38MGR, 40MAQ)
What E5 means on a Carrier
The control board is reading the indoor evaporator coil temperature sensor (T2) as open or shorted, which means the thermistor (a small resistor whose resistance changes with temperature) is returning a value outside its normal range. The unit usually stops, or runs with the wrong output, because the control board no longer trusts that temperature reading.
On this platform, E5 is a fault: something has failed or is disconnected and needs diagnosis.
Common causes
- The indoor evaporator coil temperature (T2) thermistor has failed (they do drift and fail with age and heat cycling).
- Its plug has worked loose from the control board, or a pin has corroded.
- The sensor lead is chafed, pinched or chewed, giving an intermittent open or short.
- The control board's sensor input has failed (rare compared with the sensor itself).
How to fix it yourself
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician.
- Reset the system: switch the breaker (or the outdoor disconnect) off, wait a full five minutes so the boards fully discharge, then switch it back on and restart from the remote.
- If the code comes straight back after a reset, the fault is real and not a glitch.
- With power off, locate the indoor evaporator coil temperature sensor (T2) pushed into a small copper well on the evaporator coil, reachable with the front panel and filters removed. Follow its lead back to the board and reseat the plug firmly.
- Inspect the lead for damage along its whole length, especially where it passes through the chassis.
- If you have a multimeter, unplug the sensor and measure its resistance. A reading near zero ohms (short) or infinite (open) confirms a bad sensor. Most mini split thermistors read roughly 5 to 20 kΩ at room temperature, so a value in that range with a steady drift as you warm it in your hand means the sensor is fine and the board is the suspect.
- Replacement thermistors are inexpensive and plug in. Match the part number from the parts list for your model.
Switch off power at the breaker before opening either unit. Capacitors in the outdoor unit hold a charge for several minutes after power is cut.
When to call a technician
Sensor swaps are a doable DIY job on most units. Call a technician if the sensor tests good and the code persists, because that points at the control board.
Which Carrier units show E5
This page applies to Carrier Comfort 38MHRB / 40MHHQ, Comfort 38MGR / 40MGQ, Performance 40MAQ / 38MAQ, Infinity 40MPHA / 38MPRA and Carrier multi-zone units on the indoor display, classic two-character codes (38MHRB, 38MGR, 40MAQ). Carrier's own documentation lists E5 as "Evaporator coil temperature sensor (T2) open or short circuit", the same definition used across the Midea platform (classic codes) it is built on. If your unit shows a code with a different shape (for example a four-character code, or a plain number), it is from a different table; use the lookup with your exact code.
Where Carrier shows this code
indoor display, classic two-character codes (38MHRB, 38MGR, 40MAQ): The code appears on the indoor unit's LED display in place of the set temperature. Some models also blink the indicator lamps in a pattern that matches the code. E codes are faults in the indoor unit or its communication link, F codes are faults on the outdoor side, and P codes are protections: the outdoor unit has stopped itself to prevent damage. EC is the refrigerant leak check.
Other Carrier codes
Same part of the system as E5:
E5 on other brands
The same characters do not always mean the same thing. Check the brand on your unit.
- Pioneer E5 Evaporator coil temperature sensor (T2) open or short circuit / Over-voltage or under-voltage protection (outdoor display)
- Blueridge E5 Over-current protection / Evaporator coil temperature sensor (T2) open or short circuit
- Gree E5 Over-current protection
- Zone Air E5 Model configuration or mismatch error
- Daikin E5 Compressor motor lock or overload
- Mitsubishi Electric E5 Indoor unit signal transmitting error (to remote controller)
- Trane E5 Model configuration or mismatch error / Indoor unit signal transmitting error (to remote controller)
- Arctic King E5 Evaporator coil temperature sensor (T2) open or short circuit
- Heil E5 Evaporator coil temperature sensor (T2) open or short circuit / Over-current protection
- ACiQ E5 Evaporator coil temperature sensor (T2) open or short circuit / Model configuration or mismatch error
Questions people ask
Can I reset a Carrier E5 code myself?
Yes. Turn the system off at the breaker for five minutes, then restart it. If E5 comes back, the fault is real and needs the checks above.
Is it safe to keep running a Carrier showing E5?
The unit will usually refuse to run, or run with reduced output, until the fault is cleared. Repeated resets do not fix anything and can mask a problem that is getting worse.
Do I need a technician for Carrier E5?
Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. Sensor swaps are a doable DIY job on most units. Call a technician if the sensor tests good and the code persists, because that points at the control board.
Sources
- Carrier 38MHRB Single Zone Ductless Service Manual SG-38MHRB-01 (Diagnosis and Solution section)
- Carrier 40MAQ / 38MAQ High-Wall Ductless Service Manual 40MAQ-01SM (Diagnosis and Solution section)
- Carrier 40MPHA / 38MPRA Infinity High Wall Ductless Service Manual (error code table)
Updated September 2026. Codes and definitions vary by model year. If your manual disagrees with this page, your manual wins. Send a correction.