Mitsubishi Troubleshooting
Mitsubishi Mini Split Error Codes — What They Mean
Your Mitsubishi wall unit is blinking, or the remote is showing a letter-number code. Here's what the common codes mean in plain English, what's safe to check yourself, and which ones mean shut it down and call.
Anatomy of the system
Numbered parts below match the cost table further down — so you can see exactly where the failure usually sits.
Common Mitsubishi error codes
Codes vary by series (wall units show blink patterns; ducted and kumo cloud systems show alphanumeric codes). These are the ones we see most on Brooklyn M-Series and P-Series systems.
| Code | What it usually means | What to do |
|---|---|---|
| E1 – E5 | Remote control can't talk to the indoor unit | Try fresh batteries and point the remote directly at the unit. If it persists, call. |
| E6 / E7 | Indoor unit can't talk to the outdoor unit — wiring or board fault | Call — this needs a tech with a meter. |
| P1 | Intake air sensor fault | Call — usually a sensor replacement. |
| P2 | Pipe (coil) sensor fault | Call — usually a sensor replacement. |
| P4 | Drain float switch tripped — condensate is backing up | Switch the unit off to stop the leak risk, then call. |
| P5 | Drain pump problem | Switch the unit off and call. |
| P6 | Coil freeze or overheat protection kicked in | Check the filter first. If it's clean and the code returns, call. |
| P8 | Abnormal pipe temperature — often a refrigerant issue | Call — refrigerant work needs an EPA-licensed tech. |
| U1 / UH | High pressure or current abnormality at the outdoor unit | Shut the system down and call. |
| U6 | Compressor overcurrent — compressor is struggling | Shut the system down and call. |
Exact code lists differ by model and series. If your code isn't here — or the light is just blinking in a pattern — text a photo or video to (347) 997-3360 and we'll tell you what it is.
Signs and symptoms
What to notice before calling a technician. The red callouts mean stop and call us immediately.
- 1
Find the code
On most Mitsubishi wall units the operation light blinks in a repeating pattern, or the code shows on the remote / kumo cloud app. Count the blinks between pauses — that count is the code. Write down exactly what you see before resetting anything.
What to notice
- Note the code on the remote display, if there is one
- Count the blinks between pauses on the unit's light
- Note which head is showing the fault, if you have several
Still not working? Call (347) 997-3360 — diagnostic visits are flat-rate, quoted before we start.
- 2
One safe reset — once only
Turn the system off with the remote, flip its breaker off for 60 seconds, then power back up. If the code comes back, that's your answer — the fault is real. Repeated resets don't fix anything and can mask damage that gets more expensive to repair.
Don't keep resetting a P4, P5, U1, or U6
Drain faults can dump water into your wall, and pressure or compressor faults can destroy the outdoor unit if you keep forcing it to restart. One reset, then call. - 3
Check the two basics
A clogged filter or blocked airflow causes a surprising share of protection codes (like P6). Slide the filter out and look at it. Also make sure nothing is blocking the indoor unit's intake or the outdoor unit's fan.
What to notice
- Look at the filter — replace or rinse if it's gray with dust
- Notice whether the outdoor unit's fan spins when the system runs
Still not working? Call (347) 997-3360 — diagnostic visits are flat-rate, quoted before we start.
- 4
Text us the code
A photo of the blinking unit or the remote display tells us most of what we need before we arrive — which means we show up with the right parts. Text it to (347) 997-3360 with your address and we'll tell you honestly whether it needs a visit.
What this usually costs in Brooklyn
When a technician diagnoses the issue, here's the typical cost range for the repair. The exact number depends on parts, access, and how long it's been failing.
| Issue | Likely cause | Typical range |
|---|---|---|
| Diagnostic visit | Confirm what's behind the code | $125 – $225 |
| Sensor / thermistor replacement | P1, P2 and similar sensor codes | $175 – $375 |
| Drain service or float switch | P4 — condensate backing up | $150 – $350 |
| Drain pump replacement | P5 — failed condensate pump | $250 – $550 |
| Communication wiring / board repair | E6, E7 — indoor-outdoor comm faults | $250 – $700 |
| Refrigerant leak search & repair | P8 and pressure-related codes | $275 – $950 |
| Indoor or outdoor PCB replacement | Board-level faults | $350 – $850 |
Diagnostic visit
Confirm what's behind the code
$125 – $225
Sensor / thermistor replacement
P1, P2 and similar sensor codes
$175 – $375
Drain service or float switch
P4 — condensate backing up
$150 – $350
Drain pump replacement
P5 — failed condensate pump
$250 – $550
Communication wiring / board repair
E6, E7 — indoor-outdoor comm faults
$250 – $700
Refrigerant leak search & repair
P8 and pressure-related codes
$275 – $950
Indoor or outdoor PCB replacement
Board-level faults
$350 – $850
Typical range. Final cost confirmed on site after diagnosis.
Common Questions
What to do next
Call (347) 997-3360 or book a diagnostic. Tell us what you observed — the sounds, the symptoms, when it started — and we'll know exactly what to check.
Do not attempt any repairs yourself. Gas, electrical, and refrigerant work requires a licensed technician.
Need a Brooklyn tech today?
Same-day diagnostics when we can fit you in. Flat-rate visit, quoted before we start.
(347) 997-3360