- HVAC
- Air conditioner
E4
Mitsubishi Electric E4 on an air conditioner: no remote signal
Risk level
Low
Usually safe to check without specialist tools.
Urgency
Medium
Quick answer
On Mr. Slim PKA units, E4 means the indoor unit board is not receiving data from the wall remote or from another indoor unit in the group. Note the code, do one reset from the breaker and, if it returns, have the remote cable checked.
Safety first
Stop and check this first
- The remote cable runs to the indoor unit's board: do not disconnect or splice it yourself. Mitsubishi Electric asks for all supply circuits to be disconnected before any terminal is accessed.
Safe checks you can perform
- Identify E4 on screen or by blinks
- How many remotes and units are grouped
- One reset from the unit's breaker
- Remote line and board diagnosis
Leave these tasks to a qualified professional
- Do not attempt this professional task: Remote terminal check at the indoor unit
- Do not attempt this professional task: Test with Remote controller check
- Do not attempt this professional task: Address 0 board review in groups
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Remote terminal check at the indoor unit
What they doThe technician inspects the remote cable connection at the indoor unit terminals and fixes loose contacts.
They must show youthe state of the remote terminals in the indoor unit before and after.
In writingcode E4, terminals inspected and the fix made.
Test with Remote controller check
What they doThey run the remote check from the service menu before deciding whether to replace the remote or the board.
They must show youthe RC OK, RC NG or RC E3 result on the screen.
In writingthe result obtained, part replaced and why it was chosen.
Address 0 board review in groups
What they doIn group control, if replacing one indoor board does not clear E4, they check the board in the unit at refrigerant address 0.
They must show youwhich unit holds address 0 and how its board was checked.
In writingunit addresses, boards replaced and the final test with its date.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Identify E4 on screen or by blinks
- Who:
- you.
- How:
- on the wired remote, E4 shows on the screen and under Error information in the main menu. With the wireless remote, press CHECK twice, select the address with TEMP and press HOUR towards the receiver: E4 gives 9 blinks with beeps, a pattern it shares with E5.
- Result that matters:
- being sure of the code before calling, since E4 and E5 have different causes.
- If you read E4 on the screen:
- continue with this page.
- If you only count 9 blinks:
- note it may be E4 or E5 and let the technician confirm it with the wall remote.
- Evidence to keep:
- a photo of the screen or a video of the 9 blinks with the date.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
How many remotes and units are grouped
- Who:
- you, observing.
- How:
- note how many wall remotes control the unit and whether one remote runs several indoor units. With two remotes, check under Initial setting, Main/Sub option, how each is set, without changing other settings.
- Result that matters:
- giving the technician what they need to check address 0 and the remote setup.
- If every remote reads Sub:
- that is one cause the manual ties to E4 on the outdoor board; mention it or set one to Main.
- If there is a single remote and a single unit:
- the technician will focus on the cable and the boards.
- Evidence to keep:
- the number of remotes and indoor units, and a photo of the Main/Sub setting.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
One reset from the unit's breaker
- Who:
- you, at the fuse box.
- How:
- stop the unit with the remote, switch off its breaker and wait for the screen and lamps to go out. Restore power, bearing in mind the manual says the remote shows PLEASE WAIT for about 2 minutes while the system starts.
- Result that matters:
- whether the indoor unit regains the remote signal after a cold start.
- If the unit responds and E4 does not return:
- write down the day and time in case it repeats.
- If E4 returns:
- leave the unit off and call the technician instead of resetting again.
- Evidence to keep:
- the time power was cut, the time E4 returned and the operating mode in use.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
Remote line and board diagnosis
- Who:
- an HVAC technician.
- How:
- checks for loose remote cable connections at the indoor unit, that the wiring keeps within 500 m total and avoids three-core or larger cable, and runs Remote controller check. With RC OK they cycle the power, and if E4 persists the manual says to replace the indoor controller board.
- Result that matters:
- whether the cable, the remote or the address 0 indoor board is at fault.
- If the check gives RC NG:
- the manual says to replace the wall remote.
- If a board was replaced in group control and nothing changed:
- the manual points to the indoor board at address 0.
- Evidence to keep:
- the check message, connections inspected and any board replaced.
The remote connections sit beside the indoor unit's board and supply: technician only, with everything disconnected.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- HVAC
- Brand
- Mitsubishi Electric
- Product type
- Air conditioner
Known code variants
- Bosch E4
- calentador Junkers E4
- Daitsu E4
- E04
- E 4
- E401
- E402
- E403
- E421
- E422
- E423
- E431
- E432
- E433
- Electrolux cooker E4
- Electrolux hob E4
- Electrolux hob E401 overheating
- Electrolux induction hob error E4
- Electrolux placa E4
- error E4 lavadora Haier
- error E4 lavavajillas Fagor
- error E4 placa inducción Electrolux
- Fagor 3LVF-623.1 E4
- Fagor dishwasher E4
- Fagor dishwasher error E4
- Fagor dishwasher overflow E4
- Fagor lavavajillas E4
- Haier E4 error washer
- Haier E4 lavadora
- Haier washer E4 not filling
- Haier washing machine E4
- Hydronext 5600S E4
- Hydronext 5700S E4
- Junkers E4
- lavadora Haier E4 no coge agua
- lavavajillas Fagor rebose E4
- Mitsubishi E4
- Mitsubishi Electric E4
- Mr. Slim E4
- PKA E4
- placa Electrolux E401 sobrecalentamiento
- vitro Electrolux E4
What it means
In service manual OCH639 for the PKA-A24/30/36KA7 indoor units, E4 is a remote controller signal receiving error: the indoor controller board gets no normal data from the remote controller board or from another indoor board for 3 minutes, or no signal at all from the remote for 2 minutes. On the wireless remote it shows as 9 blinks. It is the mirror of E0: here the indoor unit is the side not hearing. Other models may use it differently. E4 shows where communication breaks down but does not prove which part is faulty.
Warnings and stop conditions
- Mediumeditorial warning
The remote cable runs to the indoor unit's board: do not disconnect or splice it yourself. Mitsubishi Electric asks for all supply circuits to be disconnected before any terminal is accessed.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
Symptoms and causes
Probable causes · in order
- Poor contact on the remote cableCommon
The manual puts first a poor contact on the transmission wire, either at the indoor unit terminals or at the wall remote.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
- Setup with no main remotePossible
When every remote is set as sub, Mitsubishi Electric says the outdoor board LEDs show E4 while the remote shows E0.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
- Indoor board at address 0Possible
A failure of the receive circuit on the indoor board at address 0; in group control the manual warns it may be that board and not the one replaced.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
- Remote with a damaged send circuitPossible
If the remote itself does not transmit properly the indoor unit stops receiving it; the remote check identifies this with the RC NG message.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
- Interference on the transmission lineLess common
Noise entering through the remote cable and stopping the indoor board from reading the data, as listed among the manual's causes.
Evidence: Mitsubishi Electric split-system heat pump service manual OCH639, indoor units PKA-A24KA7, PKA-A30KA7, PKA-A36KA7
Virtual technician
Does E4 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Mitsubishi Electric · 2016 · manual
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