Mira A fault codewhat it means and how to fix it
Flashing red on the Status light. Mira group three water-supply problems under this one code: no supply, low pressure, or a blockage somewhere in the outlet.
Take care
What A means
Code A is Mira telling you that the shower cannot get the water it needs, and they deliberately do not distinguish between the three reasons for that, because the checks overlap and an owner can work through all of them in a few minutes. The appliance cannot tell the difference either. All it knows is that its flow sensing says there is not enough water moving, and since heating a tank that is not flowing is the thing an electric shower must never do, it stops. The three published causes are worth taking in order of how easy they are to rule out.
No water supply is the trivial one and it happens more than people expect, usually because a servicing valve on the inlet has been left partly closed after other work. Low pressure is the seasonal and time-of-day one — a shower on a mains supply that is marginal will fail at seven in the morning and work perfectly at ten. Blockage is the one that develops slowly and is by far the commonest on an installation more than a couple of years old, and Mira name four places to look: the filter, the hose, the showerhead and the bleed valve.
Two of those four are yours and two are not. The hose and the showerhead come off from outside. The inlet filter and the air bleed button are inside the case, and Mira’s own maintenance section has the filter cleaned by a tradesperson with the cover off and the appliance re-primed before the power goes back on. One more thing from Mira governs how you do any of this: if the shower shows low or no flow from the outlet, they say to turn it off at once and not to operate it, and any further diagnosis is done with the power control on low and the temperature control at full cold.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Blockage in the outlet — head, hose or filter | Scale in the spray plate, a collapsed hose liner, or silt in the inlet filter inside the unit. The commonest of the three and the one that builds gradually. | Common |
| Incoming water pressure too low | A marginal mains supply that drops below what the shower needs at peak times. Works later in the day and fails at breakfast. | Common |
| Water supply off or a valve part-closed | The servicing valve on the inlet pipe left partly shut after other plumbing work. Costs nothing to check and is the first thing Mira ask. | Occasional |
| Debris in the flow valve | Grit sitting in the valve so it does not open fully. Established behind the cover; Mira’s published remedy for a flow valve fault is customer services. | Occasional |
What to try yourself
Confirm the water is on, including the small servicing valve on the pipe feeding the shower. Mira put this first and it is worth doing first.
Set the power control to low and the temperature control to full cold, take the showerhead off and start the shower with the bare hose into the tray. If the flow is strong with the head off, the head is your blockage.
Those two settings are Mira’s condition for diagnosing a low-flow symptom at all. Their warning is that a shower showing low or no flow is turned off immediately and not operated, and that any further diagnosis is done on low power and full cold.Descale or replace the showerhead, and check the hose passes water freely on its own — a liner can collapse inside a hose that looks perfect.
Run a cold tap fed from the same main to judge the pressure arriving at the house. Mira’s second check is the water pressure, and a weak tap means the supply rather than the shower.
If the head and hose are clear, the water is on and the pressure is good, stop. The other two places Mira name, the inlet filter and the bleed valve, are inside the unit, and their maintenance section has the filter cleaned by a tradesperson with the cover off and the shower re-primed before the electricity is restored.
Do not remove the cover to reach the filter. Mira print that there are no user-serviceable components beneath it and that mains connections are exposed when it is off.
Get a qualified electrician to look at your Mira A
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified electrician, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What it costs to fix
Typical repair cost
£0–£120
Time on site
25 minutes
Usually nothing beyond a new showerhead or hose. A filter clean on a Mira is a short visit, because it is behind the cover and the unit is re-primed afterwards. If the flow valve itself has to be replaced you are into a visit and a part.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Mira fault codes
- DGet it checkedFlashing red and yellow. The outlet thermistor has seen a temperature above what Mira allow, and the shower has stopped rather than deliver it.Related: same brand
- MUsually simple to fixFlashing white. Not a breakdown — the shower was switched off at the cord before it finished its shutdown, and it will not restart properly until it settles.Related: same brand
- LGet it checkedStatus light off entirely, with Start/Stop off. Mira call this an electrical fault and the action is to check power to the shower.Related: same brand
- FGet it checkedFlashing red and blue with Start/Stop flashing. The cold water arriving at the shower is already hotter than Mira allow it to be.Related: same brand
- IGet it checkedFlashing red and white with Start/Stop flashing. Mira call it a software error, and their published remedy is simply to power cycle the unit.Related: same brand
- CGet it checkedFlashing red and yellow with Start/Stop off. A thermistor fault: the shower has lost the temperature sensing it relies on to stay safe.Related: same brand
Own a Mira electric shower? Save it and its codes come first next time.
Related guides
Common questions about Mira A
Why does one code cover three different problems?
Because the shower cannot tell them apart. It senses insufficient flow and stops; whether that is a closed valve, weak mains or a scaled head is something only you can establish, and Mira give you the checks in order.
The rest of the house has good pressure. Can it still be low pressure?
Yes, if the restriction is between the main and the shower — a part-closed servicing valve, a kinked flexible tail, or a filter that has silted up. Pressure at the kitchen tap does not prove pressure at the shower.
What is the bleed valve Mira mention?
The air bleed button inside the unit, held down during priming to let trapped air and water out of the heater tank. It is behind the cover, so although Mira list it alongside the filter, hose and head as one of the four things to check, it is a tradesperson’s check rather than yours.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.