DIY HVAC Tools

Carrier mini split error code P6

Outdoor low pressure protection.

  • TypeProtection
  • SystemRefrigerant circuit
  • Can I fix it?Homeowner checks, then maybe a tech
  • Applies toindoor display, classic two-character codes (38MHRB, 38MGR, 40MAQ)

What P6 means on a Carrier

Suction pressure dropped below the safe limit, which usually means the refrigerant charge is low or the flow is restricted. The compressor stops to avoid running dry.

On this platform, P6 is a protection: the system stopped or throttled itself to prevent damage; many clear on their own once conditions return to normal.

Common causes

  • Low refrigerant charge from a leak or an incomplete charge at installation.
  • A service valve not fully open, or a kinked line set.
  • A badly iced or blocked indoor coil in cooling mode (frozen coil).
  • A failed low-pressure switch or sensor.

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.

  1. Confirm both service valves are fully open.
  2. Pull the front panel and check the filters and the indoor coil. Dirty filters and a matted coil restrict airflow, and airflow problems trigger a surprising number of protection codes.
  3. If the indoor coil is iced over, leave the unit in Fan-only mode until it thaws, then retry.
  4. Leak-check the flare joints (see EC).
  5. Anything inside the refrigerant circuit (sensors are fine, but valves, compressors and leaks are not) needs EPA-certified refrigerant handling. That is a technician job.

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

A technician must measure the charge with gauges. Do not add refrigerant without finding and fixing the leak.

Which Carrier units show P6

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 P6 as "Outdoor low pressure protection", 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 P6:

ECRefrigerant leak detected (low refrigerant charge)EL 0CRefrigerant leak detected (low charge)PC 03Pressure protection (high or low pressure switch)PC 0ACondenser high temperature protection
E0Indoor unit EEPROM parameter errorE1Communication error between indoor and outdoor unitsE2Zero-crossing signal detection errorE3Indoor fan speed out of control (indoor fan motor fault)E4Indoor room temperature sensor (T1) open or short circuitE5Evaporator coil temperature sensor (T2) open or short circuitF0Overload current protection (compressor over-current)EBCommunication error between indoor main board and display board

All Carrier error codes

P6 on other brands

The same characters do not always mean the same thing. Check the brand on your unit.

  • Pioneer P6 Outdoor low pressure protection / Inverter module (IPM) malfunction (outdoor display)
  • Blueridge P6 Communication error between inverter drive and main controller / Outdoor low pressure protection
  • Gree P6 Communication error between inverter drive and main controller
  • Zone Air P6 Cooling mode overheating protection
  • Mitsubishi Electric P6 Freeze protection (cooling) or overheat protection (heating)
  • Trane P6 Cooling mode overheating protection / Freeze protection (cooling) or overheat protection (heating)
  • Arctic King P6 Outdoor low pressure protection
  • Heil P6 Outdoor low pressure protection / Communication error between inverter drive and main controller
  • ACiQ P6 Outdoor low pressure protection / Cooling mode overheating protection

Questions people ask

Can I reset a Carrier P6 code myself?

Yes. Turn the system off at the breaker for five minutes, then restart it. If P6 comes back, the fault is real and needs the checks above.

Is it safe to keep running a Carrier showing P6?

Not repeatedly. A protection code means the unit stopped itself to prevent damage, and resetting it over and over can turn a cheap repair into a compressor failure. Reset once, check the basics, and stop if it returns.

Do I need a technician for Carrier P6?

Work through the checks below first; they resolve most cases. If they do not, the repair itself may need a technician. A technician must measure the charge with gauges. Do not add refrigerant without finding and fixing the leak.

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.