BoilerFaultCodesVaillant F.87 Fault Code
Also written as F87 — same fault.
The Vaillant F.87 fault code means: your boiler has detected a problem with the internal ignition components, meaning it cannot safely light the burner to provide heat or hot water.. It appears on 24 Vaillant models in our database.
Technical description: Fault: Electrodes. Electrodes not connected or they are connected incorrectly, short circuit in the cable harness
What causes the Vaillant F.87 fault?
This fault occurs when the boiler's control board loses communication with the components responsible for creating the spark and sensing the flame. It is usually caused by a loose connection, damaged wiring, or electrodes that have worn down and can no longer complete the electrical circuit required to start the boiler. Without this secure connection, the system shuts down as a safety precaution to prevent unburnt gas from entering the combustion chamber.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Vaillant models that show the F.87 fault code
Click a model for the full fault code list and model-specific repair notes.
- ecoFIT pure Repair: £150-250
- ecoFIT Pure 412 Repair: £150-250
- ecoFIT Pure 418 Repair: £150-250
- ecoFIT Pure 425 Repair: £150-250
- ecoFIT Pure 435 Repair: £150-250
- ecoFIT Pure 825 Repair: £150-250
- ecoFIT Pure 830 Repair: £150-300
- ecoFIT Pure 835 Repair: £150-250
- ecoTEC plus Repair: £100-£250
- ecoTEC Plus 610 Repair: £120-250
- ecoTEC Plus 615 Repair: £100-£250
- ecoTEC Plus 620 Repair: £100-£250
- ecoTEC Plus 625 Repair: £100-£250
- ecoTEC Plus 630 Repair: £100-£250
- ecoTEC Plus 635 Repair: £100-£250
- ecoTEC Plus 65 Repair: £100-£250
- ecoTEC Plus 832 Repair: £100-£250
- ecoTEC Plus 836 Repair: £100-£250
- ecoTEC Plus 840 Repair: £100-£250
- ecoTEC Plus 938 Repair: £100-£250
- ecoTEC plus Regular Repair: £120-250
- ecoTEC plus System Repair: £150-300
- ecoTEC sustain Repair: £100-£250
- Home System Repair: £120-£250
Source
Vaillant F.87 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026