Vaillant VU 446/5-5 / VU 606/5-5 fault F.10

Flow temperature sensor short circuit

Gas boiler

What it means

Flow temperature sensor short circuit detected.

Likely causes

  1. NTC sensor defective
  2. Short circuit in the wiring harness
  3. Defective heating flow or return temperature sensor

Where to start

  1. Check the wiring harness.
  2. Pull out the heating flow (4) and return temperature sensor (3)
  3. Remove the heating flow (1) and return plug (2)

The full answer, free

  • How to put it right, step by step
  • The manual page for this fault (page 60), 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 Vaillant manual for the VU 446/5-5 / VU 606/5-5. Check the model on the data plate before you order parts.

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