Breville Bambino Plus Not Heating or Coffee Not Hot Enough? Fixes

Here’s the thing that surprises new Bambino Plus owners: the machine itself heats almost instantly — Breville’s ThermoJet system is ready in a few seconds — so “my coffee isn’t hot enough” is very rarely the heater failing. It’s nearly always the cold stuff the hot coffee touches: a room-temperature cup, a cold portafilter, a cold group. Two ounces of espresso has almost no heat to spare, and cold metal drinks it up before the cup reaches your hand.

So this guide splits cleanly. If your coffee is merely lukewarm, the fixes are free and take seconds. If the machine genuinely never gets hot — water stays cold, lights flashing — that’s a different, rarer problem, and we’ll cover that too.

First, which problem do you have?

• Coffee comes out warm but not hot → thermal mass: preheat the cup, portafilter and group (Causes 1–3). This is almost everyone.
• Milk isn’t hot enough, but espresso is fine → that’s steam, not brew heating (Cause 4).
• Water genuinely never gets hot, lights flashing → scale or a fault (Causes 5–6).

Quick diagnosis

Cause 1 — Cold group and portafilter (the main reason for lukewarm shots)

What it looks like: The shot is warm at best, especially the first of the session; it improves a little after the machine’s been used.

Why it happens: The ThermoJet heats the water, but that water immediately hits a cold group head, a cold portafilter and a cold basket, which pull the temperature down before it reaches the cup.

The fix — run a blank shot first:

1. Lock the empty portafilter into the group.
2. Run a single-cup shot of plain hot water through it into your cup.
3. Tip the water out, dry the basket, then dose and brew straight away while everything’s hot.

This one step warms the group, portafilter, basket and cup together and is the biggest single improvement you can make.

Cause 2 — Brewing before the buttons are solid

What it looks like: Inconsistent temperature depending on how quickly you start.

Why it happens: The buttons flash while the ThermoJet heats and go solid when it’s at temperature. Start while they’re flashing and you catch it before it’s ready.

The fix: Wait the few seconds for solid buttons, do your warm-up flush, then brew. Unlike a boiler machine you don’t need a long wait — just don’t jump the gun on a cold start.

Cause 3 — Cold cup and slow serving

What it looks like: The shot leaves the group hot enough but is lukewarm by the time you drink it, especially with milk.

Why it happens: A cold cup and added cold milk drop the final temperature fast.

The fix: Preheat the cup (the warm-up flush from Cause 1 does this, or fill it with hot water and tip it out), steam your milk to a good temperature, and serve promptly. Don’t pour a hot shot into a cup straight from the cupboard.

Cause 4 — Milk not hot enough (it’s a steam issue)

What it looks like: The espresso is hot, but milk drinks come out cool.

Why it happens: The automatic steam wand stops at a set temperature, and a too-low setting — or a partly blocked wand — leaves milk cool.

The fix: Raise the temperature setting on the milk controls, make sure the wand is primed and the tip is clear, and purge before steaming. For the full diagnosis (wand won’t reach temperature, blocked tip, plant-milk tips), see the steam wand guide.

Cause 5 — Scale insulating the ThermoJet

What it looks like: The machine gradually runs cooler and flows more weakly than it used to, often with the descale light on.

Why it happens: Limescale coats the ThermoJet’s heating path and narrows its waterways, so it transfers less heat to the water.

The fix: Run a full descale cycle with a proper descaler — see our descaling guide. In hard-water areas this is essential, recurring maintenance, and it commonly restores heat and flow at the same time.

Cause 6 — Genuinely won’t heat (fault state)

What it looks like: The water never gets hot at all and the buttons keep flashing without settling, or the machine won’t complete a shot.

Why it happens: That’s a fault rather than a warm-up issue — most often the tank ran dry or the machine overheated, occasionally a ThermoJet or control fault.

The fix:

1. Turn off at the wall and unplug for 60 seconds.
2. Make sure the tank is full and seated — never run it dry.
3. Let it cool for 20–30 minutes if it’s been working hard.
4. Power back on and watch the start-up.

If it heats normally afterwards, you’re done. If the flashing persists, see the error-lights guide — a fault that survives a reset, water and a cool-down needs Breville service, as there’s little user-serviceable inside.

Common mistakes that make it worse

• Skipping the warm-up flush and judging the machine on a cold first shot.
• Brewing into a cold cup with cold milk, then blaming the heater.
• Confusing cool milk with a brew-heating fault — check the steam setting first.
• Never descaling, so heat and flow slowly fade in hard water.
• Cycling a flashing, faulted machine repeatedly instead of resetting it properly or contacting Breville.

Repair or replace?

For lukewarm coffee, there’s nothing to repair — it’s preheating and serving technique, all free, plus descaling on schedule. Those fix almost every case. A genuine ThermoJet that won’t heat after a reset and descale is the only scenario that points to service, and because the Bambino isn’t built for owner repairs, that’s a warranty claim or a service-centre job rather than a parts swap. Try the free steps first; they resolve the overwhelming majority of “not hot enough” complaints.

Stop it happening again

• Always run a warm-up flush through the locked-in portafilter before the first shot.
• Preheat the cup and serve promptly.
• Wait for solid buttons before brewing.
• Descale on schedule for your water hardness to protect brew temperature.
• Never run the tank dry, which is what trips the fault state in the first place.