High
Communication fault on Vaillant ecoTEC plus 612 VU GB 126/5-5

Your boiler's main electronic control board has temporarily lost connection with the display screen, meaning the system cannot coordinate heating or hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

No communication with the PCB Communication fault between display and PCB in the electronics box

From this model's manual
Verified against the Vaillant/Vaillant Ecotec Plus 612 4104460 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.83View →F.84View →F.85View →

All 121 fault codes on the ecoTEC plus 612 VU GB 126/5-5

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

D.000D.001D.002D.003D.004D.005D.006D.007D.008D.009D.010D.011D.012D.013D.014D.015D.016D.017D.018D.019D.020D.022D.023D.025D.026D.027D.028D.033D.034D.035D.036D.039D.040D.041D.044D.046D.047D.050D.051D.058D.060D.061D.064D.065D.067D.068D.069D.070D.071D.072D.073D.075D.076D.077D.078D.080D.081D.082D.083D.084D.088D.090D.091D.093D.094D.095D.096D.098F.00F.01F.02F.03F.10F.11F.12F.13F.20F.22F.23F.24F.25F.26F.27F.28F.29F.32F.35F.42F.49F.52F.53F.54F.56F.57F.61F.62F.63F.64F.65F.67F.68F.70F.71F.72F.73F.74F.75F.76F.77F.78F.83F.84F.85F.91F.92F.93S.11S.16S.17S.24

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