- Boilers
- Tankless gas water heater
EE
Junkers EE on gas water heater: modulation solenoid fault
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
On Junkers Hydronext 5700S, 5600S and 2400S room-sealed gas water heaters, code EE means the modulation solenoid valve is not connected and puts the appliance into a safety lockout. Do not open the front cover: try at most one reset and contact a qualified gas technician.
Safety first
Stop and check this first
- Never remove the front casing or touch the gas valve or control box wiring yourself; Chapter 10 of the Hydronext manuals states that all installation, maintenance and repair work must be performed by qualified technicians.
- Display fault codes put the water heater into a safety lockout; do not reset the appliance repeatedly when EE remains active.
Safe checks you can perform
- Confirm code EE on the digital display and check 1F in the fault history
- Carry out a single external reset according to your Hydronext model
- Switch the water heater off and close the gas shut-off valve
Leave these tasks to a qualified professional
- Do not attempt this professional task: Check the wiring connection between the modulation solenoid valve and control box
- Do not attempt this professional task: Replace any faulty valve or control component with original parts and test for leaks
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.
Check the wiring connection between the modulation solenoid valve and control box
What they doThe qualified technician closes the water and gas shut-off valves, undoes the 2 front cover screws (Section 9.1), and inspects the plug and harness between the gas modulation valve (item 6 in the wiring diagram) and the control box (item 13).
They must show youthe condition and seating of the modulation solenoid plug at both the gas valve and the control box.
In writingthe inspection findings for the modulation valve harness and the cleared fault history (FH) check.
Replace any faulty valve or control component with original parts and test for leaks
What they doIf the harness is properly connected but the modulation solenoid coil or control box is defective, the authorised service technician fits a genuine Junkers replacement part, renews any disturbed seals, and verifies burner gas pressure and tightness (Section 9.3).
They must show youthe electrical check on the modulation solenoid coil and the post-repair gas tightness and function test with the front cover refitted.
In writingthe genuine part number installed, the verified burner pressure settings and the service report reference.
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.
Confirm code EE on the digital display and check 1F in the fault history
- Who:
- you, using only the external display panel.
- How:
- verify that the screen shows EE with the fault indicator; on Hydronext 5600S and 5700S models you can open menu P4 -> FH (Fault history) to check the latest logged code under 1F and see whether any other codes preceded it.
- Result that matters:
- confirming that the safety lockout is EE (modulation solenoid valve not connected) rather than FA, EA or EC.
- If a different fault code appears on screen or in 1F:
- follow the guidance for that specific code.
- If EE is confirmed on the display:
- write down the exact model from the rating plate on the underside of the heater.
- Evidence to keep:
- photo of the digital display showing EE (and the 1F entry in menu FH on 5600S/5700S units).
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Carry out a single external reset according to your Hydronext model
- Who:
- you, once only and provided there is no smell of gas.
- How:
- on the Hydronext 5600S and 5700S press the return symbol for 5 seconds (Resetting the appliance); on the Hydronext 2400S turn the power selector dial fully to the left to switch off and then back to the right.
- Result that matters:
- checking whether the safety lockout clears or whether EE returns immediately because the solenoid remains undetected.
- If the code clears and hot water operation resumes:
- monitor the next few hot water draws closely.
- If EE reappears right away:
- do not repeat the reset, as the manual notes the underlying fault must be fixed before resetting.
- Evidence to keep:
- note of the display response after the single reset attempt.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Switch the water heater off and close the gas shut-off valve
- Who:
- you, operating only the external controls.
- How:
- switch the appliance off using the ON/OFF button (or by turning the selector fully left on the 2400S) and close the installation gas valve before calling a qualified technician or Official Junkers Service.
- Result that matters:
- keeping the appliance safely isolated until a specialist inspects the modulation valve connection.
- If the heater is switched off and the gas tap is closed:
- give the technician the model code and fault EE.
- If freezing weather is expected while the heater is disconnected without an anti-freeze kit:
- check the draining instructions in Section 4.5 / 4.7 / 4.8.
- Evidence to keep:
- model designation, 10-digit part number and FD date code from the bottom rating plate.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
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
- Boilers
- Brand
- Junkers
- Product type
- Tankless gas water heater
Known code variants
- Bosch EE
- calentador Junkers EE
- error EE calentador Junkers
- Hydronext 2400S EE
- Hydronext 5600S EE
- Hydronext 5700S EE
- Junkers EE
- Junkers EE fault
- Junkers gas water heater EE
What it means
In the official installation and use manuals for the Junkers Hydronext 5700S (WTD 12/15/17-4AME, document 6720884104), Hydronext 5600S (WTD 12/15/17-3AME, document 6721841217) and Hydronext 2400S (WD 8/11-AME, document 6720882438) gas water heaters, display code EE stands for modulation solenoid valve not connected (Válvula solenoide de modulación no conectada) and triggers a safety lockout; the table separates EE from FA (gas valve fault). Other Junkers Bosch models may differ. On its own, EE never proves that the gas valve has failed, as a loose plug at the valve or control box causes the exact same code.
Warnings and stop conditions
- Higheditorial warning
Never remove the front casing or touch the gas valve or control box wiring yourself; Chapter 10 of the Hydronext manuals states that all installation, maintenance and repair work must be performed by qualified technicians.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Mediumeditorial warning
Display fault codes put the water heater into a safety lockout; do not reset the appliance repeatedly when EE remains active.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Symptoms and causes
Probable causes · in order
- Unplugged or loose connector at the gas modulation solenoid valveCommon
The fault tables in all three Hydronext manuals define EE as the modulation solenoid valve (item 6 in the wiring diagram) being disconnected.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Loose plug or broken wire at the control box connectionPossible
Junkers' remedy column instructs checking the connection both at the modulation valve and at the control box (caja de control, item 13).
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
- Open circuit in the modulation solenoid coil or control box outputLess common
If the harness plugs are firmly seated at both ends and EE persists, an open solenoid winding or a fault in the control box prevents detection.
Evidence: Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438) · Junkers Hydronext 5600S WTD12/15/17..., manual de instalación y uso del calentador de gas (6721841217) · Junkers Hydronext 5700S WTD12/15/17..., manual de instalación y uso del calentador de gas (6720884104)
Virtual technician
Does EE 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
Junkers Hydronext 2400S WD8/11..., manual de instalación y uso del calentador de gas (6720882438)
Junkers (Bosch Termotecnia) · 2020 · manual
- 2
Junkers (Bosch Termotecnia) · 2022 · manual
- 3
Junkers (Bosch Termotecnia) · 2021 · manual
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