DeLonghi A05 Alarm — Water Circuit Fault

What Does This Error Mean?

A05 means water isn't flowing through the machine the way it should.
Almost always this is air trapped in the pump after a tank refill or after the machine ran dry.
Run hot water through the steam wand for 15 seconds — that primes the pump.
Most A05 events clear within minutes once water flow is restored.

Affected Models

DeLonghi Magnifica S
DeLonghi Dinamica
DeLonghi Eletta
DeLonghi PrimaDonna
DeLonghi La Specialista

Common Causes

Air locked in the pump after refilling an empty tank
Tank not seated properly — no water reaching the pump
Water filter cartridge new and not yet flushed
Scale buildup blocking water flow
Pump itself failing (uncommon, usually after years)

How to Fix It

Check the water tank.

Pull the tank, refill if low, push back in firmly until it clicks.
Most A05 events happen right after the tank ran empty — refilling and reseating fixes them.
Run hot water through the steam wand.

Turn the dial to the steam/hot water position.
Run hot water into a cup for 15 seconds.
This is the standard 'prime the pump' procedure — pulls fresh water through the system and clears air locks.
Most A05 errors clear the moment water starts flowing properly.
Check for a new water filter.

If you've just installed a new CLARIS or DeLonghi water filter, it needs flushing first.
The cartridge contains air that displaces water in the pump until you run a few hundred ml through it.
The instructions on the filter packet describe the flush procedure.
Run a descaling cycle if A05 persists.

Settings > Descaling > Start.
Heavy scale narrows the water passages and triggers A05 because flow drops below threshold.
A full descale clears the deposits and restores normal flow.
Book service for repeated A05.

If A05 keeps coming back after priming and descaling, the pump may be failing.
DeLonghi pumps last roughly 5,000–8,000 brews — past that, performance degrades.
Service replaces the pump for €80–150 plus labour.

Frequently Asked Questions

Why does A05 happen mostly after refilling the tank?

Running the tank empty pulls air into the pump intake.
Refilling restores water but the air bubble stays in the pump until you flush it out.
The steam wand flush is the official procedure — opens the valve and lets water push the air through.

Can I prevent A05 entirely?

Yes — refill the tank before it runs empty.
Watch the level rather than waiting for the alarm.
Most DeLonghi tanks have a clear strip or a level indicator.
A simple habit of refilling at half-full prevents A05 and the priming step it requires.