E163 Boiler Fault Code: What It Means on Every Brand

The E163 fault code appears on 2 boiler brands — Baxi and Potterton — 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 2 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 E163 means	Severity	DIY?
BBaxi	The E163 code appears on Baxi boilers when the domestic hot water (DHW) NTC thermistor sensor develops a fault. Full guide →	Lockout — engineer likely	No
PPotterton	The E163 fault code on a Potterton boiler indicates a problem with the Domestic Hot Water (DHW) NTC (Negative Temperature Coefficient) temperature sensor. Full guide →	Lockout — engineer likely	No

E163 brand by brand

Baxi E163

The E163 code appears on Baxi boilers when the domestic hot water (DHW) NTC thermistor sensor develops a fault. The boiler's PCB uses this small temperature-sensing probe to monitor hot water temperature — its electrical resistance changes predictably as the water warms up, letting the board calculate an accurate reading. E163 covers two distinct failure states: a short circuit (s.c.), where the sensor's circuit collapses and sends a zero-resistance signal, and an open circuit (o.c.), where the circuit is broken entirely and no signal reaches the PCB. In either case, the boiler cannot safely regulate domestic hot water and locks out to protect itself. Central heating may continue to work, but hot water from taps and showers will be unavailable until the fault is resolved.

Causes, fixes & costs for Baxi E163 → · All Baxi codes

Potterton E163

The E163 fault code on a Potterton boiler indicates a problem with the Domestic Hot Water (DHW) NTC (Negative Temperature Coefficient) temperature sensor. The boiler's PCB has detected that the sensor is either reading temperatures incorrectly, has gone into short circuit, or has developed an open circuit — meaning the PCB can no longer get reliable temperature data from the hot water circuit. When this happens, the boiler will typically lock out as a safety measure and display E163 until the underlying fault is diagnosed and resolved.

Causes, fixes & costs for Potterton E163 → · All Potterton codes

Frequently asked questions

Is the E163 fault code the same on every boiler?

Broadly, yes — on Baxi and Potterton the E163 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 E163 fault myself?

Not usually. On every brand listed, E163 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 E163 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.