Furnace attempts to start but shuts down quickly, control shows flame error, intermittent heating

Safety: Isolate power and close the gas valve before removing burner components.

• Check grounding: Ensure the green/yellow ground wire from the mains is firmly attached to the Viessmann chassis. Tighten any loose ground screws.
• Clean MatriX burner surface: Remove the burner assembly following the Viessmann service instructions. Use a soft brush or vacuum to remove dust and debris from the stainless-steel MatriX burner surface. Do not use aggressive tools that can damage the mesh.
• Inspect ionization lead: Trace the ionization cable from the electrode to the control board. Look for brittle insulation, burn marks, or loose connectors. Reseat the plug on the control board. Replace the cable if any damage is visible.
• Check air intake and exhaust: Inspect the concentric flue for obstructions (leaves, nests, ice). Ensure the air intake screen is clean. Restricted air can cause unstable flame and F2 errors.
• Restart and monitor: Restore power and gas, reset the unit, and observe ignition. If the flame still drops out or the code returns, a technician should check combustion settings and gas valve operation.