Lack of water circulation in the primary circuit
The 09 error code on Sime boilers indicates lack of water circulation in the primary circuit.
Sime 09 means: lack of water circulation in the primary circuit. On this component the documented failure modes are the poor circulation of water in the primary circuit is determined by the ?t between the flow sensor (sm) and the return sensor (sr) and can occur both at start-up and during operation or no water circulation: pump blocked, seized or not running. You can safely reset the boiler once — if 09 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does 09 Mean
The 09 code is shown by the boiler’s control board when it detects lack of water circulation in the primary circuit. 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 09 and the boiler stops until the fault is cleared |
Common Causes
The first cause below is the one the Sime service literature publishes for this code (source: centriassistenza.org). The others are the failure modes documented for the same component on other boilers, confirmed by 5 different manufacturers.
| Cause |
|---|
| The poor circulation of water in the primary circuit is determined by the ?T between the flow sensor (SM) and the return sensor (SR) and can occur both at start-up and during operation |
| No water circulation: pump blocked, seized or not running |
Safety Warning
09 involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
Consult service manual
Refer to the Sime service documentation for the specific diagnosis procedure for fault code 09.
Check error log
Access the boiler error log to check for related fault codes that may help identify the root cause.
Contact manufacturer support
If the fault persists after basic checks, contact Sime technical support for specialist guidance.
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 Sime service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Sime models that can display fault code 09:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Sime models | — | Possible |
Frequently Asked Questions
09 is not classified as a high-severity fault, so the boiler can be reset once. If 09 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.