Poor circulation – ensure gas supply is turned on, if meter is a prepayment type ensure there is credit
The E4 error code on Baxi boilers indicates poor circulation – ensure gas supply is turned on, if meter is a prepayment type ensure there is credit.
Baxi E4 means: poor circulation – ensure gas supply is turned on, if meter is a prepayment type ensure there is credit. On this component the documented failure modes are no water circulation: pump blocked, seized or not running. A Gas Safe registered engineer should diagnose the root cause.
What Does E4 Mean
The E4 code is shown by the boiler’s control board when it detects poor circulation – ensure gas supply is turned on, if meter is a prepayment type ensure there is credit. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows E4 and the boiler stops until the fault is cleared |
Common Causes
The manufacturer does not publish a cause list for this specific code. The causes below are the failure modes documented for the same component on other boilers, confirmed by the service literature of 5 different manufacturers.
| Cause |
|---|
| No water circulation: pump blocked, seized or not running |
Safety Warning
E4 is a gas-related fault. Never attempt to repair or adjust the gas valve, burner assembly, or flue system yourself. All gas work must be carried out by a Gas Safe registered engineer (UK) or licensed HVAC technician (US). Repeated resets after ignition failure can cause unburnt gas to accumulate inside the combustion chamber — this is a serious safety hazard. If you smell gas at any point, turn off the gas supply at the meter, open windows, leave the property, and call your gas emergency service immediately. Gas-related fault. Do not open the boiler casing or attempt repairs to the gas valve, burner, ignition or flue. Repeated resets are unsafe. Diagnosis and repair must be carried out by a Gas Safe registered engineer.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
1. Note the exact error code and check the manufacturer's installation and service manual for specific guidance. 2. Check all visible wiring connections for security and condition. 3. Power cycle the boiler — switch off at the mains for 30 seconds, then switch back on. 4. If the fault recurs, check the fault history for related or recurring codes. 5. Inspect the boiler for any obvious signs of damage, leaks, or unusual sounds
How to Fix It
Check the pump is receiving power and turning freely; free a seized shaft or replace the pump if it does not run.
Refer to the Baxi service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Baxi models that can display fault code E4:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Baxi models | — | Possible |
Frequently Asked Questions
E4 is classified as a high-severity fault: it involves gas, combustion or flue components. Do not keep resetting the boiler and do not attempt the repair yourself — call a Gas Safe registered engineer.