- Boilers
- Tankless gas water heater
A16
Cointra A16 on gas water heater: gas valve or wiring fault
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Error A16 on Cointra CPE T and SUPREME E TS room-sealed gas water heaters signals a gas valve fault or interrupted gas valve wiring. Because A-codes cause a permanent lockout, press RESET for 1 second once; if the heater still will not start, close the gas cock and call a registered gas technician.
Safety first
Stop and check this first
- All repairs and gas valve replacements must be performed solely by registered gas technicians using original spare parts; never tamper with sealed regulators or repeatedly reset A16.
- Before opening the cover or touching internal parts, always disconnect the appliance from the electrical supply via the external isolator switch and close the gas cock.
Safe checks you can perform
- Verify code A16 on the LCD panel
- Single reset holding the RESET key for 1 second
- Test gas valve wiring harness and valve coils
Leave these tasks to a qualified professional
- Do not attempt this professional task: Check the gas valve electrical wiring
- Do not attempt this professional task: Test the gas valve and replace it if faulty
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 gas valve electrical wiring
What they doWith the heater isolated from the mains supply and the gas cock shut, the technician inspects the wiring harness and electrical connector feeding the gas valve from the PCB.
They must show youthe gas valve electrical plug and the continuity reading across the harness leads.
In writingcode A16, the condition of the wiring inspected, and any connector or harness repair performed.
Test the gas valve and replace it if faulty
What they doIf the wiring is sound, the technician tests the gas valve and, if defective, replaces it using an original Cointra spare part, then checks gas tightness and minimum/maximum burner pressures at the test points.
They must show youthe replaced gas valve if changed, the gas leak check and the burner pressure readings during modulation.
In writingthe original spare part code fitted, the gas tightness verification and the recorded burner pressures.
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.
Verify code A16 on the LCD panel
- Who:
- you.
- How:
- check the control panel LCD to confirm the fault icon is flashing with code A16 (during safety wait intervals the display may also show d3 and d4).
- Result that matters:
- confirming the water heater is in a permanent lockout linked to the gas valve circuit.
- If you smell gas near the appliance:
- do not press any buttons or electrical switches, close the gas shut-off valve, ventilate the room and call a registered gas technician.
- If there is no smell of gas and only A16 shows on screen:
- proceed with the single reset allowed by the manual.
- Evidence to keep:
- a clear photo of the LCD screen showing code A16 before pressing RESET.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Single reset holding the RESET key for 1 second
- Who:
- you, from the external control panel.
- How:
- as Cointra specifies for permanent A-series lockouts, press the RESET button for 1 second and then open a hot water tap to see whether the burner ignites.
- Result that matters:
- finding out whether the lockout was transient or whether the wiring or valve fault remains.
- If the water heater restarts and displays the DHW outlet temperature:
- use it normally and note the date in case A16 returns.
- If the unit fails to restart and displays A16 again:
- do not repeat the reset, switch the appliance off with ON/OFF and call a registered gas technician.
- Evidence to keep:
- whether the burner lit after holding RESET for 1 second or immediately locked out in A16 again.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Test gas valve wiring harness and valve coils
- Who:
- registered and authorized gas technician.
- How:
- with mains electricity isolated and the gas shut-off valve closed, remove the front casing and check continuity along the wiring harness, electrical connector I on the gas valve (24 Vdc, coil resistances around 65 ohms and 24 ohms on the SGV100 diagram) and valve operation.
- Result that matters:
- separating a broken wire or loose plug from a failed gas valve.
- If the wiring is broken or connector I is loose:
- repair the electrical connection and verify burner ignition and modulation.
- If the harness is intact but the valve coil is open or the valve fails to open:
- replace the gas valve with an original Cointra spare.
- Evidence to keep:
- measured continuity and coil resistance values at the gas valve connector and the condition of the harness.
Working on the gas valve or inside the casing involves gas tightness and 230 V mains voltage, so only a registered gas technician may perform this check.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
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
- Cointra
- Product type
- Tankless gas water heater
Known code variants
- A 16
- A16
- Cointra A16
- Cointra CPE T A16
- Cointra Supreme A16
- Cointra water heater error A16
- error A16 calentador Cointra
What it means
According to the user, installation and maintenance manuals for the Cointra CPE T and SUPREME E TS room-sealed gas water heaters, code A16 means a gas valve fault (anomalía de la válvula del gas). Like all A-series codes on these appliances, it causes a permanent lockout that halts hot water production until the RESET button is pressed for 1 second. Seeing A16 on the LCD panel does not by itself prove the gas valve assembly has failed, because an interrupted wire or loose plug between the control board and the valve triggers the exact same code.
Warnings and stop conditions
- Higheditorial warning
All repairs and gas valve replacements must be performed solely by registered gas technicians using original spare parts; never tamper with sealed regulators or repeatedly reset A16.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
- Highsource verified
Before opening the cover or touching internal parts, always disconnect the appliance from the electrical supply via the external isolator switch and close the gas cock.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Symptoms and causes
Probable causes · in order
- Interrupted wiring to the gas valveCommon
Cointra's fault table lists interrupted electrical wiring between the main circuit board and the gas valve as the first possible cause of code A16.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
- Faulty gas valve assemblyPossible
Cointra lists a defective gas valve (the 24 Vdc SGV100 gas block shown in the SUPREME E TS service section) as the second possible cause of lockout A16.
Evidence: Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03) · Cointra SUPREME E TS, instrucciones de uso, instalación y mantenimiento (cod. 3541A273 Rev.01)
Virtual technician
Does A16 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
Cointra CPE T, instrucción de uso, instalación y mantenimiento (cod. A73022110 Rev.03)
Cointra · 2018 · manual
- 2
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