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S.17

S.17 — DHW Mode Pump Overrun Error (EcoTEC Pro / EcoTEC Plus)

Vaillant · Turbomax Plus Boilers

What does S.17 mean?

This error indicates that the EcoTEC Pro / EcoTEC Plus boiler's domestic hot water (DHW) pump is running for an extended or unexpected period after the hot water demand has ceased.

Common Causes

  • DHW pump malfunction
  • Control system error

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Perform a boiler reset by switching the main power off and then on.

  2. 2

    Ensure the system pressure is adequate.

  3. 3

    If the pump continues to overrun, contact a qualified heating engineer to inspect the pump and controls.

Browse all codes in this manual (55)
Verified technical data. Last updated: April 2026

Related Faults

F.00F.00 — Flow NTC Cable Defective or Broken (Turbomax Plus)F.00, F.04, F.05, F.10, F.14, F.15F.00, F.04, F.05, F.10, F.14, F.15 — NTC Sensor Fault (Ecomax Pro 828E)F.01F.01 — Feed Temperature Sensor (NTC) Fault or Open Circuit (Turbomax Plus)
Source: Vaillant Turbomax Plus Boilers
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