- Boilers
- Tankless gas water heater
EA
Bosch EA on gas tankless water heater: no flame detected
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Error code EA on the display of a Bosch Therm 2400 F gas tankless water heater means no flame was detected within the 5-second safety window and the unit locked out. If there is no gas odor, close and reopen a hot tap and cycle the selector once; if EA returns, call Bosch service.
Safety first
Stop and check this first
- If you smell gas, do not flip electrical switches or unplug anything: close the main gas valve, open doors and windows, leave the building and call from outside.
- Never remove the front cover of the water heater or modify the flue gas duct or safety devices; all repairs must be carried out by the brand's authorized technical service.
Safe checks you can perform
- Confirm there is no smell of gas or exhaust fumes in the room
- Check that the water and gas shutoff valves are open and 127 V power is on
- Reset the safety lockout with the power selector and reopen a hot tap once
Leave these tasks to a qualified professional
- Do not attempt this professional task: Gas supply pressure measurement and gas/water tightness test
- Do not attempt this professional task: Cleaning the burner and combustion chamber and replacing the water filter
- Do not attempt this professional task: Inspection of the ignition electrode, ionization electrode and control box
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.
Gas supply pressure measurement and gas/water tightness test
What they doA trained Bosch service technician measures the inlet gas supply pressure and burner pressure, purges the gas line and tests all gas and water joints for leaks.
They must show youthe measured gas supply pressure within specification and leak-free gas and water connections.
In writingthe recorded gas pressures, verified gas type (natural gas or LPG) and the certified technician's report.
Cleaning the burner and combustion chamber and replacing the water filter
What they doDuring periodic maintenance, the accredited technician cleans the burner and combustion chamber, replaces the water inlet filter next to the flow regulator and fits new O-rings and gaskets.
They must show youthe new water filter installed and proper operation of all safety and regulation devices.
In writingthe maintenance tasks completed, new gaskets fitted and the approved technician's signature.
Inspection of the ignition electrode, ionization electrode and control box
What they doWith mains power disconnected at all poles and water and gas valves closed, the authorized technician removes the front cover to inspect the ignition electrode, ionization electrode, wiring harness and control box.
They must show youprompt burner ignition and steady flame detection on the display without code EA.
In writingthe condition of the ignition and ionization electrodes and any original replacement parts installed.
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 there is no smell of gas or exhaust fumes in the room
- Who:
- you, before touching the power selector or electrical plug.
- How:
- check the installation area for any smell of gas or combustion fumes. If you smell gas, follow page 3 of the Bosch manual: do not flip electrical switches or pull any plug, close the main gas shutoff valve, open doors and windows, leave the building and call from outside.
- Result that matters:
- confirming there is no gas leak or exhaust odor before operating the controls.
- If you smell gas or flue fumes:
- close the fuel supply, ventilate, leave the building and call the gas utility and authorized service from outside.
- If there is no smell of gas and the flue duct is intact:
- proceed to check the supply valves and power.
- Evidence to keep:
- a note confirming no gas odor was present and room ventilation openings are unobstructed.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
Check that the water and gas shutoff valves are open and 127 V power is on
- Who:
- you, next to the Bosch Therm 2400 F.
- How:
- verify that the external water and gas shutoff valves are fully open and that the power cord is firmly plugged into a live 127 V, 60 Hz outlet.
- Result that matters:
- steady electrical power and open water and gas supplies to the heater.
- If the gas or water valve was closed:
- open it fully before performing the lockout reset.
- If both valves were already open and the display shows EA with the fault indicator:
- perform a single selector reset.
- Evidence to keep:
- a photo of the digital display showing EA and the open position of the water and gas valves.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
Reset the safety lockout with the power selector and reopen a hot tap once
- Who:
- you, at the front power selector and a hot water tap.
- How:
- follow the note under Table 15 and Section 4.3 of the manual: close the hot water tap, turn the rotary power selector all the way to the left to switch the appliance off, turn it back to the right to switch it on, then open a hot water tap.
- Result that matters:
- the heater purging residual air, detecting a flame within 5 seconds and clearing code EA.
- If the burner lights and the burner-in-use icon appears:
- the lockout was caused by air in the line or a brief interruption.
- If code EA locks the unit out again:
- turn the selector fully left to switch it off and call the brand's authorized service.
- Evidence to keep:
- a note of whether EA returned after the 5-second ignition safety interval.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
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
- Bosch
- Product type
- Tankless gas water heater
Known code variants
- bloqueo EA calentador a gas Bosch
- Bosch EA
- Bosch gas water heater EA
- Bosch tankless water heater EA
- Bosch Therm 2400 F EA
- EA
- error EA calentador Bosch
- no flame detected EA Bosch
- no se detecta la llama EA Bosch
What it means
In Bosch's operating and installation manual for the Therm 2400 F gas tankless water heater (8, 11 and 14 L models, document 6 720 888 821), Table 15 defines code EA as flame not detected: if a flame is not established within the 5-second safety interval, the heater performs a safety shutoff and lockout shown on the digital display. Other Bosch models may differ, and code EA by itself never proves that a component is faulty. All work on gas supply lines, flue exhaust ducts, ignition and ionization electrodes, thermal cut-outs and 127 V, 60 Hz electrics must be performed only by the brand's authorized service technician.
Warnings and stop conditions
- Highsource verified
If you smell gas, do not flip electrical switches or unplug anything: close the main gas valve, open doors and windows, leave the building and call from outside.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
- Highsource verified
Never remove the front cover of the water heater or modify the flue gas duct or safety devices; all repairs must be carried out by the brand's authorized technical service.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
Symptoms and causes
Probable causes · in order
- Gas shutoff valve closed or air trapped in the gas supply pipeCommon
Section 3.5 of the Bosch manual explains that air in the gas supply line (at initial startup or after long periods of inactivity) delays ignition past the 5-second safety window and triggers a lockout.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
- Incorrect gas supply pressure or gas type mismatchPossible
Table 15 lists gas supply pressure as the first item to check for code EA, and Section 4.2 requires confirming that the installation's gas supply matches the rating plate (natural gas or LPG).
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
- Unstable 127 V electrical connection or interrupted hot water flowPossible
Bosch's remedy for EA includes checking the electrical mains connection and closing and reopening a hot water tap (the unit requires between 0.2 bar and 10 bar of water pressure).
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
- Fouled or faulty ignition electrode or ionization flame electrodeLess common
The Therm 2400 F troubleshooting chart directs checking the ignition electrode and the ionization electrode, marked with footnote 1 for qualified and trained technicians only.
Evidence: Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
Virtual technician
Does EA 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
Manual de instrucciones de manejo y de instalacion Calentador de paso a gas Therm 2400 F 8 11 y 14 L
Bosch Home Comfort · 2018 · official_doc
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