Baxi E193 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E193 fault code mean?
The E193 code appears on Baxi boilers when the pre-circulation check fails at start-up. Before the burner fires, the boiler briefly runs its circulation pump to confirm water is moving freely around the system. If the PCB detects that flow or temperature gradient conditions aren't met during this short test — most likely because the pump isn't shifting water properly — it triggers the E193 lockout. Because Baxi uses 'E' prefix codes to denote hard lockouts, the boiler will not attempt to restart on its own; the fault must be properly investigated and cleared before heating or hot water will resume. A related code, E125, covers primary circulation faults more broadly, while E193 specifically targets the pre-circulation phase at ignition.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Seized or sticking circulation pump Common
The pump can seize — especially after a long period of inactivity such as the summer months — meaning it fails to move water during the pre-circulation test. Air cavitation inside the pump body is another common way the pump becomes unable to deliver adequate flow.
- Air locked in the system Common
Air pockets in the pipework or heat exchanger prevent water circulating properly during the brief pre-circulation phase. Even a moderate air lock can be enough to trigger the lockout if the pump cannot push water past it.
- Magnetite sludge restricting flow Common
Over time, corroded metal particles form a dark, thick sludge inside pipework and the heat exchanger. This sludge narrows the internal bore of the circuit, making it extremely difficult for the pump to achieve the flow rate required during the pre-circulation check.
- Blocked magnetic filter Sometimes
An inline magnetic filter that has become clogged with debris will restrict flow to the point where pre-circulation cannot complete successfully. This is especially common in older systems or those without a regular servicing schedule.
- Closed or partially closed system valves Sometimes
If a lockshield valve, isolation valve, or any other system valve has been inadvertently shut off or left partially closed — perhaps after recent plumbing work — water cannot complete the circuit during pre-circulation.
How to fix it
- Check your gas supply is working DIY safe
Before anything else, confirm other gas appliances in your home (such as a gas hob) are working normally. If you have no gas at all, contact your gas supplier rather than an engineer.
- Attempt a single boiler reset DIY safe
Follow your boiler's manual to perform a reset — usually by holding the reset button for a few seconds. If the fault clears and the boiler runs normally, monitor it closely. If the E193 returns promptly or the boiler locks out again after one or two resets, stop resetting and move on — repeated resets without a fix can cause further damage.
- Check system pressure is between 1.0 and 1.5 bar DIY safe
A low pressure reading (below 0.8 bar) can contribute to circulation problems. If the pressure gauge reads low, top up the system using the filling loop — typically a braided flexible hose beneath the boiler — until the gauge reads around 1.2–1.5 bar, then close the filling loop valves. If you are unsure how to do this, consult your boiler manual or call an engineer.
- Inspect all visible system valves DIY safe
Walk around your central heating system and check that every visible valve on radiators and pipework is fully open. Lockshield valves (the capped end of a radiator valve) are particularly easy to close accidentally during decorating or furniture moving.
- Have a Gas Safe engineer diagnose and free or replace the pump Gas Safe engineer
The most common cause of E193 is a seized pump. An engineer will attempt to free the pump shaft manually before deciding whether the pump head or the entire pump assembly needs replacing. This is not a homeowner task as it involves draining sections of the sealed system and working with electrical components.
- Have the system bled and balanced professionally Gas Safe engineer
If air is suspected, the engineer will methodically bleed the system from the ground floor upward, run a pump override cycle, and recheck pressure and flow throughout the circuit. They will also check that the pump speed setting is appropriate for your system.
- Have the magnetic filter cleaned or replaced Gas Safe engineer
The engineer will inspect, clean, and refit the inline magnetic filter. If it is beyond cleaning, a replacement filter will be fitted. At the same time, they will check inhibitor levels and top up if needed.
- Consider a powerflush if sludge is the underlying cause Gas Safe engineer
If the engineer finds cold spots at the bottoms of radiators, a filter full of sludge, or restricted flow throughout the system, a powerflush or chemical flush may be recommended. A powerflush uses specialised equipment to drive cleaning solution through the entire circuit at high velocity, dislodging and removing magnetite and debris.
- Call a Gas Safe registered engineer if you have not already done so Gas Safe engineer
E193 is a hard lockout with circulation at its root — there is no homeowner-accessible fix beyond the basic checks above. A qualified Gas Safe engineer is needed to diagnose the exact cause, carry out the repair safely, and clear the lockout properly.
Parts you may need
- Circulation pump (e.g. Grundfos UPS2 or Wilo equivalent) · from £95
- Pump head only (motor cartridge replacement) · from £55
- Magnetic system filter (e.g. Adey MagnaClean or Fernox TF1) · from £45
- Inhibitor fluid (e.g. Fernox F1 or Adey MC1, 1 litre) · from £15
- System pressure gauge (if faulty) · from £20
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £150–£420, depending on the underlying cause.
Frequently asked questions
Can I reset the Baxi E193 myself and will it fix it?
You can try a single reset — sometimes a minor air bubble causes a one-off pre-circulation failure and the boiler runs normally afterwards. However, E193 is a hard lockout, meaning it will not self-clear without a reset. If the fault comes straight back, repeated resetting will not solve it and may cause further wear. At that point you need a Gas Safe engineer to identify the root cause.
What is the difference between Baxi E125 and E193?
Both codes relate to circulation problems. E125 points to an issue with primary water circulation detected during normal operation, while E193 specifically flags a failure during the pre-circulation check that happens just before the burner fires. In practice the underlying causes — seized pump, air locks, sludge — are very similar for both codes, and the diagnostic steps a Gas Safe engineer follows are largely the same.
How much does it cost to fix a Baxi E193?
For most households the repair falls between £150 and £420. A pump head replacement with labour is typically at the lower end (around £150–£250), while a full pump replacement plus call-out tends to sit around £200–£380. If a powerflush is also needed — for example because years of sludge have contributed to the fault — the total can rise to £500–£600 or more. In rare cases where the PCB has been damaged by overheating, that component alone can cost £200–£400 plus fitting, though this is uncommon with E193 specifically.
How can I prevent the E193 error from coming back?
The most effective steps are: fit and regularly clean a magnetic filter (annually at minimum), ensure the system always has the correct inhibitor level, and book a Gas Safe service every year. Engineers also recommend a full powerflush every 5 to 10 years depending on water hardness and system age. These steps limit sludge accumulation and keep the pump running freely, which removes the two most common triggers for this fault.