Potterton E193 fault codewhat it means and how to fix it
The rotary-switch Pottertons' pre-ignition pump check has failed: the pump ran and the flow never proved. Same causes as E125; no owner reset is offered.
Take care
Get a Gas Safe registered engineer to look at your Potterton E193
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
Can you hear the pump when the boiler tries to start?
The right answer depends on what you can see. Pick the one that matches.
Choose the option on the left that matches what your appliance is doing, and the answer for that case appears here.
Nothing — no hum, no vibration
The pump is not running.
Engineer; expect a pump.
It hums but E193 still appears
Running but not moving water: air or blockage, or a seized rotor.
Bleed the system, check pressure; then engineer.
What E193 means
The final row of every Promax, Titanium, Gold and Heatmax table is E193, the pre-circulation fault. It is the pump check that happens before the burner is allowed to light. When heat is called for the pump starts first, the boiler watches the flow sensor for the temperature to begin moving as water passes through, and if nothing happens within the pre-circulation period the ignition is not attempted and E193 is shown.
The Promax Combi fault-finding chart closes the central heating sequence with a single box for 125 and 193, which asks the engineer to confirm that water is circulating round the primary circuit and that nothing is blocking it — so the two codes have the same three causes: a pump that is not moving water, air where water should be, and passages narrowed by sludge.
The digital-display Assure and Promax Ultra renumber the same condition as 109 (see that page); an owner moving from a Promax to an Assure will not see 193 again. None of the rotary-switch manuals offer a reset for it, and the user guides do not mention it at all, so there is no owner procedure beyond checking pressure and bleeding radiators; if it persists it is an engineer's pump-and-flow investigation.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Pump seized or failed | The most common finding after a summer idle. Section B of the chart: 230 V at the pump connector and no rotation means a new pump. | Common |
| Air lock at the heat exchanger | After a refill the pump spins in air. The chart starts here — automatic air vent cap open, system pressure above 0.5 bar. | Common |
| Sludge or a closed valve restricting flow | Enough restriction and the flow sensor never sees moving water even with a working pump. | Occasional |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£60–£600
Time on site
1 hour
Pump £180–£300 fitted. Air vent £60–£100. Power flush £350–£600.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Magnetic system filter, 22mm
MAG-22£65–£120Plumbing merchant
Price checked 28 September 2026
Baxi / Potterton / Main pump assembly
7684006£120–£240Authorised Baxi parts distributor
Price checked 28 September 2026
Baxi / Potterton / Main automatic air vent
7207776£15–£45Authorised Baxi parts distributor
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Potterton fault codes
- E110Get it checkedSafety thermostat operated — the primary water overheated — on every Potterton code display. One reset is permitted (5 s knob or 1–3 s button); a second E110 is a circulation fault for an engineer.Related: overheat and circulation
- E125Get it checkedCirculation fault (primary circuit) on every Potterton code display — the water did not warm as expected after lighting, or overshot twice. Pump, air or sludge; an engineer job after one reset.Related: overheat and circulation
- E130Get it checkedFlue NTC operated — the flue gas got too hot — on every Potterton code display. Reset once as the user guide allows; if it returns the heat exchanger or flue needs an engineer.Related: overheat and circulation
- E109Get it checkedThe digital-display Pottertons' pre-ignition pump check — Assure Combi, Assure System, Promax Ultra. The flow never proved, so the burner was not lit. Bleed and check pressure; then an engineer.Related: overheat and circulation
- E270Get it checkedCirculation fault (dry fire) on the Potterton Assure and Promax Ultra: the burner lit with too little water passing the heat exchanger. Not resettable by the owner; engineer.Related: overheat and circulation
- E119Get it checkedThe sealed system on a rotary-switch Potterton — Promax, Titanium, Gold, Heatmax — has dropped below half a bar. The window shows E1 and then 19. Fill to 1–1.5 bar and it clears itself.Related: same brand
Own a Potterton boiler? Save it and its codes come first next time.
Related guides
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.