Junkers FB boiler code: gas valve failed its leak test

Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.

1. 1

   Check for any smell of gas near the boiler

   No special tools

   Who:

   you, without opening the casing or touching switches.

   How:

   go near the appliance and the meter and only notice whether there is a gas smell; never use a lighter or flame to look.

   Result that matters:

   knowing whether, besides FB, there is a noticeable leak.

   If confirmed:

   if you smell gas, follow this page's safety warning straight away and leave the home.

   If not confirmed:

   with no smell, go on to the single reset and the engineer call.

   Evidence to keep:

   note whether there was a smell and where you noticed it.

   Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación

2. 2

   Write down FB and cause code 365

   No special tools

   Who:

   you, from the Excellence Compact display.

   How:

   photograph the warning triangle with FB and the number 365 shown underneath; the user manual asks for the fault code and three-digit number when you contact Bosch.

   Result that matters:

   the engineer knowing from the call that this is the EV1 test.

   If confirmed:

   quote FB 365 when booking so they come prepared for the gas valve.

   If not confirmed:

   if the number shown is not 365, note whatever appears: it may be another table row.

   Evidence to keep:

   photo of FB with its cause number.

   Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación · Junkers Cerapur Excellence Compact ZWB...A..., instrucciones de instalación y manejo para el técnico (6 720 820 575)

3. 3

   Press reset one time only

   No special tools

   Who:

   you, with the reset key on the panel, as the reset section describes.

   How:

   press reset, wait for Reset on the display and watch whether the boiler starts or FB returns with the blue LED flashing.

   Result that matters:

   telling a one-off test failure apart from a valve that fails again.

   If confirmed:

   if FB returns, do not repeat it: leave the boiler off until the visit.

   If not confirmed:

   if the boiler runs, still tell the engineer an FB occurred.

   Evidence to keep:

   time of the reset and what happened after pressing.

   Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación

4. 4

   Gas valve tightness test

   Tools required

   Who:

   registered gas engineer or Junkers authorised service.

   How:

   inspect stage EV1 named by code 365 and carry out the in-operation tightness check described in the commissioning section of the installer manual.

   Result that matters:

   confirming whether the valve closes tightly or there is a real leak.

   If confirmed:

   repair or replace the valve and test tightness again.

   If not confirmed:

   if the valve passes, review the fault history before returning the boiler to service.

   Evidence to keep:

   job sheet with the tightness test result and the part worked on.

   The gas valve and any work with the casing off are reserved for a competent engineer according to the user manual.

   Evidence: Junkers Cerapur Excellence Compact ZWB...A..., instrucciones de instalación y manejo para el técnico (6 720 820 575)

A code is meaningful only inside the right product and version context.

The Cerapur Excellence Compact lockout table gives FB cause code 365, gas valve EV1 leak test failed, with gas valve leak as the possible cause and the reset key as the release. It is the boiler's own self-test of whether one valve stage closes tightly; the other stage, EV2, has its own message (FA 364). The user manual warns that some codes cannot be cleared with a simple reset and that an engineer visit must then be arranged. The code alone does not prove gas is escaping into the home.

• Criticaleditorial warning

  FB concerns gas valve tightness: if you also smell gas, do not press reset or switch lights or appliances on or off. Close the valve at the meter or regulator, open windows, leave while warning neighbours and call the emergency line from outside.

  Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación · Junkers Cerapur Excellence Compact ZWB...A..., instrucciones de instalación y manejo para el técnico (6 720 820 575)

• Higheditorial warning

  If FB comes back after a single reset, the boiler must stay off until a gas engineer tests the valve; repeated resets do not fix a leaking valve.

  Evidence: Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación · Junkers Cerapur Excellence Compact ZWB...A..., instrucciones de instalación y manejo para el técnico (6 720 820 575)

1. 1

   Junkers Cerapur Excellence Compact, instrucciones de uso de la caldera mural a gas de condensación

   Junkers (Bosch Termotecnia) · 2019 · manual

2. 2

   Junkers Cerapur Excellence Compact ZWB...A..., instrucciones de instalación y manejo para el técnico (6 720 820 575)

   Junkers (Bosch Termotecnia) · 2019 · manual