First establish whether the machine has completely lost heat or the coffee is simply cooler than expected. After the Magnifica has completed its warm-up, dispense hot water from the steam/hot-water circuit. If the water is properly hot, the heating system is operating and the problem is more likely related to coffee temperature, cup temperature, settings or extraction. If coffee, hot water and steam all remain cold, an actual heating-system fault becomes much more likely.

A Magnifica can produce correctly heated coffee that quickly feels lukewarm when dispensed into a cold, thick-walled cup. Warm the cups with hot water immediately before brewing and compare the result. This is particularly useful when the complaint is that coffee is "not hot enough" rather than completely cold. If the first drink is noticeably cooler than subsequent drinks, cup and internal machine temperature are important factors.

Magnifica versions with an adjustable coffee-temperature setting should be checked before assuming there is a heating fault. Set the machine to a higher temperature and test it again after allowing it to fully warm up. Remember that the temperature setting affects the brewing water rather than guaranteeing a particular temperature once the drink reaches the cup; cup temperature, drink volume and added cold milk will all reduce the final temperature.

Limescale inside the Magnifica's heated water circuit can interfere with heat transfer and restrict the amount of water passing through the system. A machine that has gradually developed cooler coffee, reduced water flow or slower dispensing should therefore be descaled before a heating component is condemned. Run the complete descale programme and all required rinse stages rather than simply passing descaler through the machine manually.

The different functions can provide useful clues. If the Magnifica reaches steam temperature and produces strong steam, the machine clearly has the ability to generate heat. If hot water is available but coffee is unusually cool, concentrate on brewing conditions and the coffee circuit. If the machine cannot produce properly heated coffee, hot water or steam despite completing its normal warm-up, the fault is more likely to be within the heating or temperature-control system.

If the Magnifica remains cold from startup, never produces hot water or steam, or repeatedly fails to complete its heating stage after cleaning and descaling, don't repeatedly run descale programmes hoping to restore it. At this stage an internal fault may be present. Depending on the Magnifica version, diagnosis can involve the heating assembly, temperature sensing, thermal protection, wiring or electronic control. These checks involve mains-powered internal components and are better left to a competent coffee-machine engineer.