How to Replace a Boiler Pressure Sensor (UK)
Swap the low-water-pressure sensor on Vaillant, Worcester and Baxi boilers. Cures phantom F22/EA338 lockouts.
VaillantWorcester BoschBaxiIdeal
Sensor vs gauge
The gauge on the fascia is mechanical. The electronic sensor is a separate transducer on the return manifold. A faulty sensor throws F22 or EA338 even at 1.5 bar showing.
OEM part numbers
- Vaillant ecoTEC plus — 0020219476 (F75 cure kit).
- Worcester Greenstar — 87186859270.
- Baxi 800 — 720552601.
Fit and test
Isolate and drain 200 ml only — the sensor sits on a service tap. Torque to 8 Nm, no PTFE.
Frequently asked questions
- F75 keeps coming back after sensor swap — what next?
- Check the pump PWM harness. F75 is 'pump/pressure' — sensor first, harness and pump next.
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