The E9 code on a Viessmann boiler signals a domestic hot water (DHW) tank temperature sensor fault. This sensor is specific to installations with a separate storage cylinder — not present on pure combi boilers. The boiler can no longer manage DHW production correctly. Symptoms No hot water, or uncontrolled temperature Heating still works normally…
The C5 error on a Viessmann boiler indicates a primary circulation fault — either the pump isn’t running, the flow rate is too low, or a mechanical blockage prevents water flow through the heat exchanger. The boiler locks out to avoid local overheating. Symptoms Boiler stopped, C5 displayed Cold radiators despite heating demand Sometimes abnormal…
The CL code (sometimes CL 0 or CL 1) on your Viessmann boiler is a service reminder — not a critical fault. It tells you the boiler has reached a threshold where maintenance is due. The boiler usually keeps running, but the message stays visible until a professional resets it. What CL means CL stands…
The error code F5 (with variants F5 0, F5 1, F5 8, F5 9) indicates an open circuit on the flow temperature sensor (heating flow or DHW flow, depending on sub-code). The boiler stops receiving a valid signal and goes into safety lockout. Symptoms Boiler locked out, F5 shown on the Vitotronic No heating or…
The error code B7 on your Viessmann boiler signals a coding card fault. This small electronic card is plugged into the main control board and identifies the exact boiler model + stores its factory parameters. Without it, the control logic can’t operate correctly. Symptoms Boiler completely locked out at startup B7 or « fault burner control »…
Error A9 is specific to Viessmann Vitocal heat pumps. It indicates a fault with the condensate temperature sensor — a safety sensor that monitors compressor discharge temperature and protects the refrigerant circuit. Symptoms Heat pump stopped, no automatic restart No heating (heat pump mode) — sometimes falls back to backup electrical resistance if configured Fault…
The codes FC, FD, and FF all signal that your Viessmann boiler’s burner control has tripped into a safety lockout. These codes require attention — the boiler has intentionally shut down because it detected an abnormal condition. Symptoms Boiler completely stopped, no automatic restart Red safety LED on the Vitotronic No heating, no DHW Reset…
The Viessmann error code E8 points to a domestic hot water (DHW) temperature sensor fault. Your heating usually keeps working, but hot water becomes unreliable — either cold, scalding, or cut off entirely. What does E8 mean? E8 signals a problem with the DHW temperature sensor (hot water). This sensor is specific to configurations with…
Your Viessmann boiler displays D7. This points to a burner control unit (LMU — Lambda Modulation Unit) fault, the electronics that handle ignition, modulation, and flame supervision. It’s one of the most common faults on Vitodens and Vitopend boilers installed in Luxembourg. What does D7 mean? The D7 code indicates a failure of the burner…
The Buderus Logamax Plus GB132 is one of the most-installed gas condensing boilers in Luxembourg. This guide covers the most common errors, the preventive maintenance this model needs, and the typical lifetime behaviour you can expect. GB132 at a glance Power range: 14–24 kW (wall-mounted) Condensing efficiency: up to 108% on NCV Display: LCD with…
