E19 Boiler Fault Code: What It Means on Every Brand

The E19 fault code appears on 3 boiler brands — Andrews, Biasi and Keston — and on all of them it points to the same kind of problem. The details still differ by brand (thresholds, sub-codes, reset procedure), so use the table below to jump to the page for your boiler.

Lockout — engineer likely 3 brands use this code

Which brand is your boiler?

The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.

Brand	What E19 means	Severity	DIY?
AAndrews	The E19 fault code on Andrews CWH-series water heaters signals that the system has detected water pressure below the minimum operating threshold — typically under 0.5 bar — which causes… Full guide →	Lockout — engineer likely	Some checks
BBiasi	The E19 code appears on newer-generation Biasi boilers, including the Rinnova and Rinnova Adaptive ranges. Full guide →	Lockout — engineer likely	No
KKeston	The E19 fault code on Keston boilers indicates that the temperature of the water returning from the heating circuit back into the boiler has risen above the permitted threshold. Full guide →	Lockout — engineer likely	No

E19 brand by brand

Andrews E19

The E19 fault code on Andrews CWH-series water heaters signals that the system has detected water pressure below the minimum operating threshold — typically under 0.5 bar — which causes the unit to shut down as a protective measure. In some cases the code can also point to a fault with the pressure sensor itself or, less commonly, an internal Master Board control error. The unit will not produce hot water while this fault is active. Because Andrews appliances are primarily commercial or industrial hot water heaters rather than standard domestic combi boilers, the E19 can appear across several CWH-series models, and the exact trigger may differ slightly between product variants — always cross-reference your specific model's documentation.

Causes, fixes & costs for Andrews E19 → · All Andrews codes

Biasi E19

The E19 code appears on newer-generation Biasi boilers, including the Rinnova and Rinnova Adaptive ranges. It signals an 'Auxiliary Input Probe Anomaly' — meaning the boiler's control board has detected a problem with an additional temperature sensor (an NTC probe) connected to its auxiliary input. This probe feeds supplementary temperature data to the PCB; when the signal falls outside expected parameters, is absent, or is erratic, the boiler registers E19 and locks out as a safety measure. On the Rinnova Adaptive display this code appears as E19 + A. Note that older Biasi models (Riva Plus, Garda) use ER-prefixed fault codes rather than E-codes — if your boiler shows an ER code, this page does not apply.

Causes, fixes & costs for Biasi E19 → · All Biasi codes

Keston E19

The E19 fault code on Keston boilers indicates that the temperature of the water returning from the heating circuit back into the boiler has risen above the permitted threshold. In a healthy system, return water should always be noticeably cooler than the flow water leaving the boiler — a high return temperature tells the boiler's controls that heat is not being distributed properly around the system. When this condition is detected, the boiler enters a hard lockout and stops operating until the fault is investigated and the reset button is pressed. Note that a closely related code, B19, is a temporary block (soft warning) triggered when the return temperature exceeds 95°C — if the underlying problem is not resolved, the boiler escalates this to a full E19 lockout. The related code B18 flags the same overtemperature condition but on the flow side rather than the return.

Causes, fixes & costs for Keston E19 → · All Keston codes

Frequently asked questions

Is the E19 fault code the same on every boiler?

Broadly, yes — on Andrews, Biasi and Keston the E19 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.

Can I fix a E19 fault myself?

On some brands there are safe homeowner checks first — typically system pressure, the condensate pipe in cold weather, and a single reset. The underlying repair usually needs a registered engineer. Never open the boiler casing yourself.

Who should I call about a E19 fault?

For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.

General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.