What does the Vaillant D.44 fault code mean?

Your boiler's electronic system is struggling to correctly detect the flame signal, which could lead to it locking out for safety.

How much does it cost to fix Vaillant error code D.44?

Typical repair cost for the Vaillant D.44 fault is £120-280 including labour.

Vaillant D.44 Fault Code: What It Means & How to Fix It

What the manual says

Manufacturer manual

Digitised ionisation – potential error

From this model's manual

Verified against the Vaillant/Vaillant Ecotec Plus Pro 839592 05 2006 installation & service manual.

What causes this fault?

This fault occurs when the boiler's internal computer receives an unstable or unexpected signal from the flame sensing components. It usually happens because the sensor that monitors the flame is dirty, worn out, or the electrical connection between the sensor and the main control board has become weak.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Boiler cover options

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Related fault codes

F.28View →F.29View →S.42View →

All 135 fault codes on the ecoTEC pro 24

Seeing a different code? Every code this model can display, in one place.

35 96 con Connection D,11 D.0 D.1 D.2 D.3 D.4 D.5 D.7 D.8 D.9 D.10 D.12 D.13 D.17 D.18 D.20 D.22 D.23 D.25 D.27 D.28 D.30 D.33 D.34 D.35 D.40 D.41 D.47 D.50 D.51 D.60 D.61 D.64 D.65 D.67 D.68 D.69 D.70 D.71 D.72 D.75 D.76 D.77 D.78 D.80 D.81 D.82 D.83 D.84 D.90 D.91 D.93 D.96 D.97 F.0 F.1 F.10 F.11 F.13 F.20 F.22 F.23 F.24 F.25 F.27 F.28 F.29 F.32 F.49 F.61 F.62 F.63 F.64 F.65 F.67 F.70 F.71 F.72 F.73 F.74 F.75 F.76 F.77 F.78 F70 P.0 P.1 P.2 P.3 P.4 P.5 P.6 S. 2 S. 5 S.0 S.1 S.3 S.4 S.6 S.7 S.8 S.10 S.11 S.13 S.14 S.15 S.16 S.17 S.20 S.21 S.22 S.23 S.24 S.25 S.26 S.27 S.28 S.30 S.31 S.32 S.34 S.36 S.41 S.42 S.52 S.53 S.54 S.96 S.97 S.98

Your boiler's electronic system is struggling to correctly detect the flame signal, which could lead to it locking out for safety.

What the manual says

What causes this fault?

Engineer required

Avoid the next call-out bill

Related fault codes

All 135 fault codes on the ecoTEC pro 24

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