Low
S.88 on Vaillant ecoTEC Pro

Your boiler is currently running an automatic air removal process to clear bubbles from the system and does not require a repair.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Purging programme is running. The purge programme is activated.

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This occurs when your boiler detects air trapped within the internal heat exchanger or pipework, often following a service, a repair, or after the system has been drained and refilled. The boiler automatically pauses its normal heating cycle to run the pump and internal valves to push these air bubbles toward the automatic air vent. Once the system is satisfied that the air has been purged, the boiler will return to normal operation on its own.

This code is most common in autumn when homeowners turn their heating back on for the first time or after summer maintenance work has been carried out on the radiators.

DIY fix possible

Wait approximately 5 to 7 minutes for the cycle to complete automaticallyEnsure your radiator valves are open to help move air through the systemCheck that the system pressure is between 1.0 and 1.5 bar on the display

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