Baxi Baxi 200/400/600/800 Combi 2 & System 2 Baxi 600/800/Assure System 2 and 600 Combi 2 platform fault E.04.11

VPS gas valve test failed

Gas boiler

What it means

Permanent fault requiring reset, indicating the VPS (valve proving system) gas valve test has failed.

Likely causes

  1. CO2 value out of specified range at maximum heat input
  2. CO2 value out of specified range at minimum/reduced heat input

Where to start

  1. With the boiler off turn the gas flow adjustment screw (V) fully clockwise until flush with the plastic tube (left-hand thread)
  2. Turn the gas flow adjustment screw (V) anticlockwise by the number of turns shown in the table to set combustion correctly
  3. Ensure there is a demand to turn the boiler on; if the boiler ignites go to step 7, otherwise proceed to steps 4-6

The full answer, free

  • 20 more checks in order
  • The readings and component tests from the manual
  • How to put it right, step by step
  • The manual page for this fault (page 74), right under the answer

Safety: Isolate gas and power before you open the case. If you have been into the gas side, do a tightness test, and a combustion and flue check before you hand back. Gas Safe (UK) or RGI (Ireland) work only.

From the Baxi manual for the Baxi 200/400/600/800 Combi 2 & System 2 Baxi 600/800/Assure System 2 and 600 Combi 2 platform. Check the model on the data plate before you order parts.

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