Baxi Boiler Fault Codes: E133, E1 Codes and What to Do

Most Baxi fault codes fall into three groups: the boiler can't light (E133), the water pressure is low (E118, or A.02.06 on newer models), or water isn't circulating properly (E110, E125). Baxi's official code list is split by product group, because older boilers like the Duo-tec and Platinum use E codes while the newer Combi 2 and System 2 ranges use dotted codes such as A.02.06. You can safely check the pressure, the gas supply and, in cold weather, the condensate pipe. Reset once. If the code comes back, book a Gas Safe engineer.

Which type of code do you have?

Before looking anything up, check the model name on the front or underneath the boiler, and write down the code exactly as shown, including any dots.

• Three-digit E codes (E110, E118, E125, E133, E160): Baxi Platinum, Duo-tec and EcoBlue models, plus related Potterton Assure boilers.
• Dotted codes (A.02.06, E.01.04, H.02.07): the Baxi 200, 400, 600 and 800 Combi 2 and System 2 boilers and the Assure 500 range.

People often search for a Baxi "E1" fault. On most boilers that's the start of a three-digit code like E110, E118 or E133 rather than a code on its own, so check the full display. The same number can mean something different between generations, which is why Baxi publishes separate lists. Our general boiler error codes guide explains how to find the right one.

E133: gas supply or ignition fault

E133 is the Baxi code people see most. Baxi describes it as a gas supply fault, and its list suggests checking the power supply, the sensing electrode, the spark electrode and the cable. In plain terms, the boiler tried to light and didn't see a flame.

Before calling anyone, check these:

1. Is gas reaching the house? Try the hob or another gas appliance. If nothing works, check the gas is on at the meter.
2. Prepayment meter credit. An empty meter produces exactly this fault.
3. Frozen condensate pipe. In freezing weather, E133 is often caused by the plastic pipe outside freezing. The condensate backs up into the boiler and stops it lighting. Our guide on a frozen or blocked boiler flue and condensate pipe explains how to thaw it safely with warm (not boiling) water.

If gas is available and the pipe isn't frozen, the fault is inside the boiler: the spark or sensing electrode, the gas valve, the wiring or the board. That's a Gas Safe job. If E133 keeps appearing on cold nights, get the condensate pipe rerouted or lagged, rather than thawing it every week.

E118 and A.02.06: low pressure

On older Baxi boilers, E118 means the water pressure in the heating system is low, which Baxi defines as below 0.5 bar. On the newer Combi 2 range, A.02.06 is a warning for low pressure in the heating circuit. If the pressure stays low, the newer boilers move on to H.02.07, low pressure (permanent), and stop running.

The fix is to top the system up through the filling loop to the range your manual gives, usually shown on the gauge. Our step-by-step guide on how to repressurise a boiler covers it. Some newer Baxi models have automatic filling. If you see E.02.39, the boiler tried to fill itself and couldn't reach minimum pressure within six minutes, which points to a supply problem or a large leak.

Topping up treats the symptom. If you're doing it more than once every few months, water is escaping somewhere: a weeping radiator valve, a leak under the floor, or the pressure relief valve letting by. Our guide to why a boiler keeps losing pressure explains how to narrow it down.

E110 and E125: overheat and circulation

E110 means the boiler has gone over its maximum temperature or the safety thermostat has tripped. Baxi's list names a jammed pump or air in the circuit as the likely reasons. E125 is a water circulation fault. On newer models, E.01.17 means no water circulation (permanent), and H.01.08 means the flow temperature rose too quickly, which pauses the boiler for ten minutes.

All of these mean the same thing: heat isn't being carried away from the boiler fast enough. Check the pressure first, since low pressure makes circulation worse. Then bleed any radiators that are cold at the top, check the pressure again, and reset once.

If it comes back, the usual causes are a seized or failed pump, sludge restricting flow, a blocked magnetic filter, or a valve left closed after work on the system. Sludge is common in older London systems. If your radiators are cold at the bottom or the water runs dark when bled, read our guide to the signs radiators need a power flush.

Common Baxi codes at a glance

If your code isn't here, look it up on Baxi's list for your product group rather than guessing from another model.

Resetting a Baxi boiler

Use the reset button or reset position shown in your user manual. Deal with the likely cause first: top up low pressure, thaw a frozen condensate pipe, or get gas back on. Then reset once and give the boiler a few minutes to fire.

If the same code comes back, stop. Repeated resets don't fix anything, and some faults, like overheating with a seized pump, can cause more damage each time the burner fires. Our guide on how to reset a boiler explains when a reset helps and when it doesn't.

When to call an engineer

Call a Gas Safe registered engineer if:

• E133 continues with gas available and the condensate pipe clear.
• E110, E125 or E.01.17 returns with the pressure correct.
• You're topping up the pressure regularly.
• The boiler shows a fan code (E160, E.04.13) or anything you can't find on Baxi's list.
• There's water under or inside the boiler. See our guide to a boiler leaking water.

Check the engineer's Gas Safe ID before they start; our Gas Safe engineer page explains how. If the boiler is under Baxi's warranty, contact Baxi first.

We repair Baxi boilers across London as part of our boiler repair service, and our boiler lockout page covers what happens when a boiler won't restart. Our labour is £95 an hour, the £60 call-out is waived on jobs over 2 hours, and we confirm the price, including any parts, before work starts.

Frequently Asked Questions