Medium
S.53 on Vaillant Turbomax 824/828

Your boiler has detected low water pressure and is pausing its operation for a few minutes to protect itself from running dry.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Delay mode due to lack of water in system (~2,5 mins.)

From this model's manual
Verified against the Vaillant Turbomax 824 828 installation & service manual, page 38.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.If the pressure is below 1 bar, locate the filling loop (usually a silver braided hose under the boiler).Open the filling valve to top up the system pressure until the gauge reaches 1.5 bar, then securely close the valve.

Find a Gas Safe engineer
Search the official register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like S.53: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Related fault codes

F.22View →F.73View →S.54View →

Related guides you might find useful

Boiler keeps losing pressure

Six most common causes of dropping pressure.

Read →

Low pressure — repressurise guide

Step-by-step using the filling loop.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →