E432 Boiler Fault Code: What It Means on Every Brand

The E432 fault code appears on 2 brands — Baxi and Navien — and it does not mean the same thing on each. The same two or three characters can signal a pressure problem on one boiler and an ignition fault on another, so identify your brand first and use the table below to jump to the right page.

Up to: Stop & check now 2 brands use this code Meaning differs by brand

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 E432 means	Severity	DIY?
BBaxi	The E432 fault code (sometimes shown simply as 432 on the display) indicates that your Baxi boiler has detected a problem with its electrical earth connection. Full guide →	Stop & check now	No
NNavien	The E432 fault code on Navien boilers and water heaters (commonly seen on NPE-series units) signals that the cold water inlet 2 thermistor has developed an open or short circuit. Full guide →	Engineer may be needed	No

E432 brand by brand

Baxi E432

The E432 fault code (sometimes shown simply as 432 on the display) indicates that your Baxi boiler has detected a problem with its electrical earth connection. This is an internal electrical safety fault — the boiler's control system has sensed that the earthing within the appliance is not as it should be, and has locked out as a precaution. This is distinct from common faults like low water pressure or a frozen condensate pipe; it points squarely at the boiler's electrical integrity. Because it involves the internal wiring and safety-critical earthing circuits, this fault must be properly diagnosed and resolved by a Gas Safe registered engineer.

Causes, fixes & costs for Baxi E432 → · All Baxi codes

Navien E432

The E432 fault code on Navien boilers and water heaters (commonly seen on NPE-series units) signals that the cold water inlet 2 thermistor has developed an open or short circuit. This small temperature-sensing component monitors the temperature of cold water entering the second inlet on the unit. When its resistance or voltage readings fall outside the expected range — whether because of a failed sensor, wiring damage, or a loose connection — the boiler's controls detect the fault and display E432 to protect the system. Note that the closely related code E421 refers to the cold water inlet 1 thermistor; if you see E421 instead, the fault lies with the first sensor rather than the second.

Causes, fixes & costs for Navien E432 → · All Navien codes

Frequently asked questions

Is the E432 fault code the same on every boiler?

No. E432 means different things on different brands — see the table above. Always identify your boiler's brand (it is printed on the front casing) before acting on any advice about the code.

Can I fix a E432 fault myself?

Not usually. On every brand listed, E432 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.

Who should I call about a E432 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.