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F.17

F.17 — System Polarity Error (EcoMax Pro)

Vaillant · Turbomax Plus Boilers

What does F.17 mean?

This fault indicates an issue with the electrical polarity of your EcoMax Pro boiler system, which needs to be corrected for safe and proper operation.

Common Causes

  • Incorrect electrical polarity

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Switch off the boiler at the main electrical supply immediately.

  2. 2

    Do not attempt to rectify electrical issues yourself.

  3. 3

    Contact a qualified electrician or heating engineer to check and correct the system's electrical polarity.

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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