S.98 — Flow-/Return-sensor check running, demand blocked

What does S.98 mean?

The boiler is performing a check of both the flow and return temperature sensors. During this process, any demand for domestic hot water (DHW) or heating is temporarily blocked. This is usually a temporary status.

• Boiler performing internal diagnostic check.
• Temporary sensor reading discrepancy.

Click steps to track your progress.

1. 1

   Wait a few minutes for the boiler to complete its sensor checks. Operation should resume automatically.

2. 2

   If the status persists for an extended period, try resetting the boiler by pressing the reset button (if available) or cycling the power.

3. 3

   If demand remains blocked after a reset, contact a qualified service technician to inspect the flow and return sensors.