Code Lookup Across Brands
P1 Error Code on Air Conditioners
Seeing a P1 error code air conditioner display can feel cryptic, yet the meaning becomes clear once you know the brand. On Mitsubishi Electric equipment, P1 is an indoor room temperature sensor fault. On Daikin’s larger ducted, Sky Air and VRV systems, P1 is a power supply problem involving voltage imbalance or a missing phase. Other brands mostly use different code formats.
The Two Main Meanings
Is P1 a Sensor Fault or a Power Fault?
It depends on the maker, and the difference is significant. One meaning points to a small thermistor inside the indoor unit. The other points to the electricity feeding the outdoor unit, often on three phase installations. Each leads to a very different visit.
Mitsubishi Electric P1
The room or intake air thermistor, usually labelled TH1 in service manuals, is reading open or short circuit. Without a believable room temperature, the controller cannot decide when to run, so it stops and flags P1.
Daikin P1
Daikin’s own error code reference lists P1 on its Sky Air, VRV and packaged ranges as power voltage imbalance or open phase. Possible causes include a missing phase, unbalanced phases, a faulty main circuit capacitor or a poor wiring contact.
In both cases, the code tells you where the system lost confidence, not exactly which part failed. A plug, a cable or a board could sit behind either version. As a result, testing always comes before replacement, and a good technician will explain each reading as they go.
Notice that Daikin applies this meaning to its larger systems. We did not find P1 listed for Daikin’s residential room air wall splits. So if a Daikin wall split shows something that looks like P1, check the display carefully and confirm it before acting.
Brand Directory
What Does Each Brand Say About P1?
This directory covers the eight brands we book most often. We list a meaning only where it was confirmed. Otherwise, we explain the brand’s own format and send you to its library.
Confirmed meanings
- Mitsubishi Electric: room or intake temperature thermistor abnormality. Full guide at Mitsubishi P1.
- Daikin: power voltage imbalance or open phase on Sky Air, VRV and packaged systems. More codes in the Daikin library.
Not confirmed or different format
- Mitsubishi Heavy Industries: uses E plus a number. No P1 meaning confirmed.
- Panasonic: letter plus two digits, such as H14 for the room sensor. No P1 confirmed.
- Samsung: mostly letter plus three digits. No standalone P1 confirmed.
- Fujitsu: two character codes from lamps or controller. No P1 confirmed.
- LG: CH plus a number. No P1 confirmed on split systems.
- Actron: E plus a number on ducted controllers. No P1 confirmed.
For the brands without a confirmed P1, use their own library to find the matching fault: Panasonic codes, Samsung codes, Fujitsu codes, LG codes and Actron codes. The Mitsubishi library covers both Mitsubishi Electric and MHI.
Equivalent Faults
What Is the Room Sensor Code on Other Brands?
Many owners searching for P1 actually want to know about a room temperature sensor fault. Every inverter system has one, but each brand labels it differently. The list below shows equivalents we have confirmed in our own brand guides.
- Mitsubishi Electric uses P1 for the intake or room air thermistor.
- Panasonic uses H14 for an indoor intake air temperature sensor abnormality.
- Samsung uses E121, often shown as E1 then 21, for the indoor room temperature sensor.
- Fujitsu uses code 41 for the room temperature thermistor.
- LG uses CH01 for the indoor room air sensor.
- Actron uses E3 on Que, Neo and L Series controllers for a sensor fault, usually the room sensor.
Keep in mind that sensor codes on other brands are not simply renamed versions of P1. Each manufacturer sets its own thresholds and its own response, so the board may stop immediately on one brand and limp along on another. That is why each linked page describes the fault for that brand alone.
These equivalents share a theme. The board has lost a reading it trusts, so it stops rather than guess. Sensor faults rarely damage anything else, which makes them one of the less urgent code families.
Which One Is Yours
How Can You Confirm the Brand and System Type?
Because Daikin uses P1 on larger systems and Mitsubishi Electric uses it on most indoor units, knowing both the brand and the system type matters. A few quick observations sort it out.
Check the badge
The maker’s name is printed on the indoor unit or the wall controller. Mitsubishi Electric and Mitsubishi Heavy Industries are separate companies, so read the full name.Read the compliance label
A sticker on the indoor unit or outdoor unit lists the model number and the electrical supply. Three phase supply is usually marked clearly.Identify the system style
Ducted systems have ceiling or floor vents and a wall controller. Wall splits have a single indoor unit high on the wall. Cassettes sit flush in the ceiling.Note the controller
Wired controllers often show P1 directly with a unit address. Wall splits may blink lamps instead, so film the pattern.Photograph everything
One photo of the code and one of the label give the technician what they need to confirm the meaning.
Mitsubishi Electric Owners
Why Does a Mitsubishi Electric Unit Show P1?
The intake thermistor is a small temperature sensor that sits in the airflow entering the indoor unit. The controller compares its reading with your set temperature, then decides how hard to run. When that reading becomes impossible, the controller stops.
Loose plug
The sensor connects to the indoor board through a small plug. Vibration over years, or a previous service, can leave it slightly unseated.
Failed sensor
Thermistors age. Their resistance can drift or fail completely, giving the open or short reading that triggers the code.
Board fault
Less often, the input on the indoor board that reads the sensor has failed. A technician rules out the sensor first.
On some ducted systems, the room temperature can also be read at the wired controller. Depending on settings, a technician will check which sensor the system is actually using before replacing anything.
Daikin Larger Systems
Why Does a Daikin Ducted or Commercial System Show P1?
Larger Daikin systems often run on three phase power. Each phase should deliver similar voltage. If one phase drops out, or the phases drift too far apart, the inverter can be stressed. Therefore, the system stops and raises P1.
Supply side causes
A blown fuse on one phase, a failed circuit breaker pole, or a problem in the street supply can all leave one phase missing or weak. Neighbours sometimes notice flickering lights at the same time.
Wiring contact causes
A loose or corroded connection at the isolator, the switchboard or the outdoor terminal block can create resistance on one phase. Heat damage around a terminal is a warning sign.
Internal causes
Daikin’s reference also lists a faulty main circuit capacitor. That is a component inside the outdoor electronics, and it must only be tested by a qualified technician.
Power quality problems can affect other equipment too. So if your home or business has other three phase machinery, mention whether it has behaved oddly lately.
Owner Checks
What Is Safe to Check Before Booking?
A few observations are safe for anyone. They do not involve opening the unit or touching electrical parts. If you see scorch marks, smell burning, or a breaker trips again, stop and leave the system off.
- Record P1 exactly as shown, with any unit address or sub code on the controller.
- Check the switchboard for tripped breakers, paying attention to multi pole breakers on three phase systems.
- Notice whether lights or other appliances flickered or lost power around the time P1 appeared.
- On wall splits, make sure curtains, furniture or a heater are not blocking airflow into the indoor unit.
- Clean the indoor filters if they look dusty, since restricted airflow can confuse readings on some models.
- Power cycle once at the breaker and note whether P1 returns immediately or after some running time.
Write your observations down while they are fresh. Times, weather and anything unusual in the house all help.
Please do not reset breakers repeatedly. On a power related P1, repeated restarts against a missing phase can harm the compressor drive. One reset tells you enough.
When to Call
How Urgent Is a P1 Code?
A sensor version of P1 is inconvenient but rarely dangerous. The system simply stops. A power version deserves faster attention, because supply problems can affect more than the air conditioner.
Call today
P1 on a three phase system with flickering lights, a hot smell near the switchboard, or a breaker that trips again after reset.
Book this week
P1 on a Mitsubishi Electric unit that returns after one reset, with no other symptoms in the home.
Watch and note
A single P1 after a blackout that cleared and has not returned. Keep a note in case it reappears.
For businesses, a power related P1 can affect trading, especially in summer. Note which other equipment shares the supply, such as refrigeration or lifts, because a phase problem may affect those too. Pass that information on when you book.
If you suspect a supply problem affecting the whole property, your electricity distributor may also need to be contacted. The technician can advise whether the fault is inside or outside your property.
On Site
What Will the Technician Actually Test?
The visit follows a logical order, starting with the simplest checks and moving inward. Knowing the sequence helps you understand the findings and any recommendation that follows.
For a sensor P1
First, the technician reads the stored error history. Next, they check the sensor plug on the indoor board, then measure the thermistor’s resistance against the manufacturer’s chart at room temperature. Only if the sensor passes do they test the board input.
For a power P1
The technician measures voltage on each phase at the switchboard and at the outdoor unit. They compare the readings, look for heat damage at connections, and check the main circuit components inside the outdoor electronics.
After any repair, the system runs through a full cycle while the technician watches readings. That confirms the fault has cleared rather than simply paused. In addition, they will usually clear the old code from memory so any new fault stands out.
Open more detail
Sensor replacements are usually straightforward, because thermistors are small parts held in clips. However, getting to them on a ducted indoor unit can mean working in the roof space. A safe access hatch and a clear path through the ceiling make the job quicker.
Power faults sometimes turn out to sit outside the air conditioner altogether. If the technician finds a supply problem upstream of your switchboard, they will explain what they measured so you can raise it with your electricity distributor or an electrician.
Avoiding a Repeat
Can You Reduce the Chance of P1 Returning?
Some causes are simply wear, and nothing an owner does will prevent them. Even so, a few habits lower the odds of both versions of P1 and of related faults on other brands.
- Book regular servicing, so terminals and plugs are inspected before corrosion or heat damage causes a fault.
- Keep the outdoor unit clear of garden growth and stored items, which helps cooling and makes connections easier to inspect.
- Fit surge protection at the switchboard if your area sees frequent storms, after discussing it with a licensed electrician.
- Ask for air conditioner wiring to be checked after switchboard upgrades or major electrical work.
- Clean filters regularly, so the indoor unit draws an even airflow past its sensors.
None of these steps guarantee a fault free system. However, they catch many small problems early, when repairs are simpler and less disruptive.
Local Conditions
Do Australian Conditions Affect P1 Faults?
Storms and supply disturbances are the main local factor for the power version. Summer storms in Brisbane and Sydney, and occasional severe fronts in Melbourne and Adelaide, can leave one phase of a three phase supply damaged or unstable.
Coastal salt affects both versions. Terminals in beachside homes and businesses corrode over time, which raises resistance on supply connections and on small sensor plugs alike. Meanwhile, roof spaces in Perth and Adelaide get extremely hot in summer, which ages cable insulation and connections around ducted indoor units.
Renovations can play a part too. Switchboard upgrades and new circuits sometimes disturb existing air conditioner wiring. If P1 appeared shortly after electrical work, mention it when booking.
Book a Technician
How Do You Arrange a P1 Repair Near You?
Rapid Air Cooling is a booking service. We arrange visits from independent licensed technicians and dispatch them to your address. We are not a dealer or agent for any manufacturer, and the technicians we send hold the licences their work requires.
We arrange repairs in all five mainland capitals. See our pages for Sydney repairs, Melbourne repairs, Brisbane repairs, Perth repairs and Adelaide repairs. Our home page explains our air conditioning service Australia wide.
When you call, tell us the brand, whether the system is ducted or a wall split, and whether it runs on single or three phase power if you know. That helps us send the right technician.
Questions
Frequently Asked Questions
What does P1 mean on a Mitsubishi Electric?
It means the indoor room or intake air thermistor is reading open or short circuit. The system stops until the sensor circuit is repaired.
What does P1 mean on a Daikin?
On Daikin Sky Air, VRV and packaged systems, P1 means power voltage imbalance or open phase. We did not find it listed for Daikin room air wall splits.
Is P1 the same on Mitsubishi Heavy Industries?
We could not confirm a P1 meaning for MHI, which uses E codes. Check the badge to be sure which Mitsubishi you own.
Can a dirty filter cause P1?
Not directly, since P1 on Mitsubishi Electric is an electrical sensor fault. Still, cleaning the filter is worthwhile and rules out airflow problems.
Should I reset the breaker for P1?
Once is fine. If P1 returns, especially on a three phase system, leave it off and book a technician.
My Panasonic shows a room sensor fault. Is that P1?
No. Panasonic uses H14 for the room air sensor. Use the Panasonic library and its remote check routine.
Is a P1 repair expensive?
It depends on the cause. A loose plug is a simpler fix than a failed board or supply fault. The technician will explain the findings before any part is replaced.
Related Reading
Where Else Can You Look?
P1 Showing on Your Controller?
Share the brand, model and a photo of the code. We will book a licensed technician to find the cause.
Reviewed by AC repair and service specialist on 22 October 2026. How we write our articles