Error C2

{ "ai_overview": "C2 on a Keston S30 System boiler is a fault code reporting a problem with the Boiler Chip Card (BCC). The BCC is a small module or programmed element associated with the boiler’s control electronics/PCB that provides configuration, identification and sometimes calibration data. When the boiler detects a BCC fault it means the control electronics are not getting valid data or communication from that chip/card or the PCB has detected an internal configuration/board fault related to the chip.\n\nSeverity is moderate to high: the boiler may lock out or run unreliably while this fault is present, and it affects the boiler’s control and safety systems. It is generally not a simple mechanical fault like low pressure and therefore most repairs require specialist knowledge, diagnostic equipment and safe handling of gas/electrical components. Basic checks and a reset can be done by a homeowner, but replacing or repairing the BCC or the PCB should be done by a Gas Safe registered engineer (in the UK) or a qualified service engineer, and by Keston service if the unit is under warranty.", "troubleshooting": "Safety first: If you smell gas, leave the property immediately and call the gas emergency number. Do not attempt any internal repairs. Only perform the simple external checks below. Isolate mains power to the boiler before removing covers — only a competent, certified engineer should open and work on the control electronics or gas components.\n\nInitial homeowner checks you can do safely:\n1) Note the exact display message and take a photo (useful for the engineer).\n2) Try a controlled restart: press the Restart button once and allow the boiler to attempt its ignition/initialisation sequence. Wait and observe for any change. Do not repeatedly press restart; too many resets in a short time can cause additional lockouts.\n3) Check mains supply: ensure the boiler isolator or fused spur is ON and the household has mains electricity. Check other electrical appliances to confirm mains supply. If you suspect low mains voltage, contact an electrician or your supplier.\n4) Check gas supply: make sure other gas appliances work or that the meter/isolation at the meter is on. If there is no gas supply, the boiler will fault for unrelated reasons.\n5) Verify external controls: ensure the programmer/timer, room thermostat and cylinder thermostat are set to call for heating/hot water and that the boiler mode knob is set to BOILER ON (and CH temp turned up). If the boiler is not being asked to run it may show other messages.\n6) Check system water pressure (cold) and confirm it is roughly between 1 and 1.5 bar if your boiler has a pressure gauge. If pressure is very low, follow manual steps to repressurise or call an engineer — do not operate the boiler with incorrect pressure.\n7) Check for condensate blockages if your system is exposed to freezing conditions: blocked condensate can cause lockouts and intermittent faults (more commonly L2) and should be cleared or thawed safely.\n\nIf you are competent and confident (and only after isolating mains power), limited additional visual checks you can consider:\n8) With the mains isolated and boiler powered down at the isolator, remove the outer cover only if you are comfortable doing so and the manual permits access. Look for obvious signs of damage on the PCB and chip card area: loose plug connectors, a partially seated card, water ingress/corrosion, burnt components or blown board fuses. Do NOT probe live circuits.\n9) If the BCC is a plug-in card that is designed to be removable and you are comfortable with ESD precautions and the boiler is isolated, you may carefully reseat the card and connectors and then restore power to test. If you are in any doubt do not attempt this — leave it for the engineer.\n\nWhen to call a professional:\n10) If the restart does not clear the fault, if the fault returns, if you see burn marks/water/damaged components, or if you are not confident to carry out the limited visual checks above, stop and call a Gas Safe registered engineer (or your local certified service engineer). The BCC error commonly requires diagnostic equipment, firmware/configuration checks and often replacement of the chip card or PCB which must be done by a qualified person. If the boiler is under warranty, contact Keston or the installer first.\n\nWhat to tell the engineer or Keston:\n11) Provide the exact error code (C2), the boiler model and serial number, a description of what you tried (restart, pressure check, photos), and any other fault codes that appeared. That information speeds diagnosis and helps the engineer bring the right parts.\n\nImportant reminders:\n- Do not attempt to repair or replace the PCB or gas valve yourself unless you are a qualified Gas Safe (or equivalent) engineer.\n- Avoid repeated restarts; frequent resets may create further lockouts.\n- If you detect a gas smell, isolate gas at the meter, leave the property and call emergency services.