Hitachi Error Code Keeps Coming Back After a Reset, What Now?

You did everything right. You noted the code, turned the power off, waited and switched it back on. For a while, the system ran. Then the same code appeared again, and now you are back where you started.

If your Hitachi error code keeps coming back, it can feel like the reset failed. In truth, the reset worked as designed. It cleared the message, then the system ran its checks, found the same problem and stopped to protect itself. This guide explains how to read that pattern and what to do next.

Why does a reset not fix the fault?

A reset is a restart, not a repair. It wipes the alarm from the control boards and gives the system a clean slate. If the cause was brief, such as a power dip, the system may then run normally.

However, most faults have a physical cause. A drain may hold a plug of slime, a sensor may read wrong or a fan motor may be wearing out. None of these change when the power goes off and on. So the system finds the same fault on the next run and raises the same code.

The system is protecting itself

Hitachi systems use alarms as protection. When a reading goes outside a safe range, the system stops before damage can happen. That is a good thing, even though it is frustrating.

Think of the code as a smoke alarm. Pressing the button stops the noise, but it does not put out the fire. In the same way, a reset silences the code, while the cause keeps going.

What does it mean when a Hitachi error code keeps coming back?

In plain terms, it means the cause is still present. The code is pointing you toward something that needs attention. The trick is to use the pattern of the return as a clue, rather than seeing it as a failure.

A repeat code usually falls into one of four groups. Each group points to a different kind of problem, so it helps to work out which one you have.

• Constant faults, such as a sensor that has failed open
• Load faults that build up as the system works, such as a blocked coil or a weak fan
• Intermittent faults that come and go, such as a loose plug or a damaged wire
• Weather faults, such as an overload on a very hot day

Once you know the group, you can give a technician far better information. You will also know whether more resets have any chance of helping.

How fast does the code return, and what does that tell you?

The timing of the return is one of the most useful clues you have. Start a timer when you restore power, then note when the code reappears. That single number can narrow the search a great deal.

Straight away, before the system starts

If the code returns within seconds, the boards are finding the fault during their start up checks. This often points to a sensor, a setting or a wiring fault. For example, a thermistor that reads open or shorted shows up before anything else runs.

Setup codes also behave this way. On wired controller systems, codes such as 31, 35 and 36 relate to capacity, unit number or combination settings. These do not fix themselves, because the settings stay the same after a reset.

After a few minutes of running

A code that waits a few minutes often points to something that happens under load. The compressor has started, pressures have built up and the system has started to work. Then something goes outside its safe range.

High pressure, high discharge temperature and overcurrent faults often fit this pattern. Dirty coils, a weak outdoor fan or a refrigerant problem can all push readings up over time. These need hands on testing, because a reset cannot clean a coil or fix a leak.

Hours later, or only some days

A code that comes back after hours, or only on certain days, often points to a fault that comes and goes. Loose plugs, damaged wires and failing parts can all work fine one moment and fail the next. Heat, cold and vibration can make the difference.

These are the hardest faults to find, because the system may look fine when the technician arrives. That is why a written log, covered below, is so valuable.

Why does the weather seem to trigger the code?

Many owners notice that a Hitachi error code keeps coming back only on very hot or very cold days. This is a real pattern, and it has a clear reason. Extreme weather pushes the system closer to its limits.

On a hot day, the outdoor unit has to reject more heat into air that is already warm. If the outdoor coil is dusty or blocked, pressures and temperatures climb faster. Codes 41 and 02 can then appear, because the system detects overload or high pressure.

Cold mornings and heating faults

In winter, the outdoor coil can ice up while the system heats. Hitachi systems defrost the coil from time to time, which is normal. However, a fault in a sensor or the defrost process can lead to repeat alarms, such as code 42 for overload in heating.

So if your code only appears in certain weather, mention that when you book. It points the technician toward airflow, coil condition and load related faults.

How should you keep a fault log?

A fault log is a simple record of when the code appears. It turns a vague worry into clear evidence. Even a few entries can save a technician a lot of time.

Use a note on your phone or a sheet of paper near the controller. Each time the code shows, write a short line with the details below.

• The code, plus the unit number if one shows beside it
• The date and the rough time of day
• What mode the system was in and the set temperature
• The outside weather, such as hot, humid, cold or stormy
• How long the system ran before the code appeared
• Whether you reset it, and what happened after the reset

After a few entries, patterns often stand out. For instance, you may notice the code only appears in heating mode, or only after long runs. That is exactly the kind of detail a technician needs.

Photos and short videos

A photo of the controller screen is useful, because it captures the code exactly. A short video is even better for wall splits, where you count blinks on the timer lamp. Play it back slowly, and count with care.

How many times should you reset before you stop?

For most codes, one or two careful resets are reasonable. If the same code returns after that, more resets are unlikely to help. They may even make some problems worse.

On wired controller systems, Hitachi uses the EE alarm as a built in limit. The system raises EE when certain alarms happen three times within six hours. In other words, the system itself is telling you that repeated restarts are not solving the problem. You can read more on our EE alarm page.

Codes that need special care

Some codes point to faults that can cause damage if the system keeps restarting. Treat these with extra caution, and stop after a single reset.

Also stop at once if you notice water, smoke, a burning smell or a breaker that trips. These signs point to a safety issue, not just a stubborn code.

Did you do the reset the right way?

Sometimes the code returns because the reset was too short or missed a power source. Before you give up, check that the steps covered the whole system. Then try once more if it seems safe.

For example, a ducted system may have a separate isolator at the outdoor unit. If you only turned off the controller, the boards never lost power. Our guides on resetting a ducted system and resetting a wall split walk through each step for those system types.

Leave the power off long enough

The boards hold some charge for a short time after the power goes off. If you switch back on too quickly, they may not reset fully. Wait several minutes, then restore power and give the controller time to load before you press run.

What simple checks might stop the code returning?

A few owner checks can help with load related codes. They do not involve opening the unit, and they are worth doing before you book. However, they will not fix a failed part.

• Clean the indoor filters as the owner manual describes.
• Clear leaves, plants and stored items from around the outdoor unit.
• Check that return air grilles and supply vents are not blocked by furniture.
• On ducted systems, make sure enough zones are open for the fan to move air.
• Look at the drain outlet outside and make sure it is not buried or crushed.

If any of these were a problem, fix it and try a single reset. If the Hitachi error code keeps coming back even after these checks, the cause is most likely inside the system.

What a good log entry looks like

Here is a simple example of the level of detail that helps. Tuesday afternoon, hot and still, cooling at the usual setting, code 41 after about an hour, reset once, back again after another hour. That one line tells a technician the fault builds under load in hot weather.

Compare that with a note that simply says the code came back. The second note is true, but it gives no direction. So spend the extra few seconds, because the details are what make the log useful.

What happens when the code changes each time?

Sometimes a reset brings back a different code instead of the same one. This can feel confusing, yet it is useful information. Often, one fault leads to another as the system tries to cope.

For example, a weak fan may first cause a temperature alarm, then a pressure alarm on the next run. A loose communication wire may cause different link faults depending on when it drops out. Write down every code in the order it appeared, because the sequence matters.

What does a technician do with a repeat fault?

A technician starts where a reset stops. They read the code on the controller and the seven segment display on the outdoor board. Next, they look at the alarm history, if the system stores it, and compare it with your log.

Then they test the parts behind the code. A sensor fault may mean measuring a thermistor and replacing it through our sensor replacement service. If a board is to blame, the fix may be PCB repair or a new board. Pressure and temperature faults, on the other hand, may need refrigerant checks.

Refrigerant faults need a licence

Any work on the refrigerant side needs a licensed technician in Australia. That includes finding leaks, recovering gas and recharging the system. You can learn about the licence through the Australian Refrigeration Council.

Why some faults need more than one visit

Intermittent faults can be hard to catch. The technician may need to check plugs, wiring and parts while the system runs under load. Sometimes they will clean or replace the most likely part first, then ask you to keep logging. That approach is normal and honest, because guessing would waste your money.

Is a repeat code a sign the system is failing?

Not always. Many repeat codes come from small, fixable issues, such as a blocked drain, a dirty coil or a single failed sensor. Once a technician fixes the cause, the code stops.

However, on an older system, a repeat code can be the start of a wider decline. If several major parts are failing at once, it may be worth weighing a repair against a new system. Our repair or replace guide covers the questions to ask.

The short answer on codes that will not clear

When a Hitachi error code keeps coming back, the code is telling you the cause is still there. A reset clears the message, but it cannot clean, repair or replace anything. So the return is a clue, not a failure.

Note when the code comes back, keep a short log and do the simple owner checks. Then stop after one or two resets, especially for drain, compressor and inverter codes or an EE alarm. At that point, the best next step is to book a technician and hand over your notes.

More Hitachi guides

• How to Reset Hitachi Air Conditioner Systems the Right Way
• Hitachi Split System Indoor Fan Not Spinning, Normal Pause or Fault?
• Hitachi Split System Turns On Then Off, How to Find the Cause

Frequently asked questions