Mitsubishi Electric air conditioner fault codes
Mitsubishi run a public error code lookup on their own UK site giving the cause and the check procedure for each code, which makes them the best documented brand here. One thing to know before you use it: several codes return more than one row, each headed by the product it was written for — often the Ecodan heat pump — and on some codes every row is for the heating side. The fault is the same whichever machine you have; the checks are written for a particular one, so read the heading as well as the code.
Where the code shows on a Mitsubishi Electric
Two schemes run side by side and Mitsubishi label which is which. Two-character codes belong to A-Control, Mr Slim and M-Series splits — the domestic and light commercial equipment. Four-digit codes belong to M-NET, used on City Multi, Lossnay and central controllers. There are even published bridge codes that translate a split’s two-character fault onto the M-NET side, so a four-digit code can be reporting a two-character one. How you see the code depends on the controller. A wired controller shows it as two characters. On a wireless remote the unit reports by counting: Mitsubishi’s Mr Slim self-check is CHECK twice, the temperature buttons to set the address, then HOUR with the remote pointed at the unit, and the indoor unit beeps and blinks the OPERATION INDICATOR lamp a number of times — five for P5, for instance — with the lamp held on for about three seconds first if the fault is in the outdoor unit. The domestic MSZ wall units on a wireless remote do the same thing by blink count and never show a two-character code at all; Mitsubishi’s owner instruction for a blinking lamp is to stop and consult the dealer. One more thing to settle first: Mitsubishi’s Ecodan heat pumps use the same two-character codes, and where a code appears on both, U1 and EF for instance, Mitsubishi’s lookup publishes the same fault, with the check rows written for the heating side. If your Mitsubishi heats radiators or a hot water cylinder rather than blowing air from a wall unit, the Mitsubishi Electric pages in our heat-pumps section carry the Ecodan checks.
How to reset a Mitsubishi Electric
Mitsubishi publish an owner reset for exactly one code in this set, and it is worth knowing because it is rare: for a non-defined error caused by noise interference their remedy is to power the system down for thirty seconds and switch it back on. The drain codes carry a related instruction aimed at engineers rather than owners: for a high condensate level, clean the drains out and then reboot the power to the outdoor unit; and the service manuals say the water-leakage code PA is not released until the main power is reset, so on that one a controller reset does nothing. For everything else the check procedures involve DIP switches inside electrical enclosures, service menus behind a password, and gauges on the refrigerant circuit — all of which is installer work at minimum. The controller offers a Reset error prompt, but clearing a code is not the same as fixing what caused it, and a logged code is not a live one.
Most common Mitsubishi Electric faults
The Mitsubishi Electric codes people look up most.
- PAGet it checkedA drain fault. Mitsubishi tell their own engineers not to assume the pump has failed — the usual cause is a blockage backing the water up.
- U1Get it checkedU1 is a high-pressure fault on a Mitsubishi air conditioner and on an Ecodan alike. The fault is the same; the checks depend on which appliance you have.
- 2503Get it checkedA drain sensor fault, which is the version where the tray is clean. Mitsubishi note the indoor unit may have a float switch instead of a sensor.
- EFUsually simple to fixA non-defined error that Mitsubishi attribute to noise interference, with a published owner remedy: power down for thirty seconds.
Every Mitsubishi Electric fault code
4 published codes. Filtering happens in the page — every one is in the HTML.
Showing 4 of 4 codes
| Code | What it means | Severity |
|---|---|---|
| PA | A drain fault. Mitsubishi tell their own engineers not to assume the pump has failed — the usual cause is a blockage backing the water up. | Get it checked |
| U1 | U1 is a high-pressure fault on a Mitsubishi air conditioner and on an Ecodan alike. The fault is the same; the checks depend on which appliance you have. | Get it checked |
| 2503 | A drain sensor fault, which is the version where the tray is clean. Mitsubishi note the indoor unit may have a float switch instead of a sensor. | Get it checked |
| EF | A non-defined error that Mitsubishi attribute to noise interference, with a published owner remedy: power down for thirty seconds. | Usually simple to fix |
Mitsubishi Electric models
Codes can differ between generations. Check yours.
Guides that help with Mitsubishi Electric faults
Looking for Mitsubishi Electric’s own support? les.mitsubishielectric.co.uk. We are not affiliated with Mitsubishi Electric.