Baxi E119 Error: Water Pressure Switch Open
Clear Baxi boiler error code E119.
The hydraulic pressure sensor microswitch contacts have opened due to central heating system pressure dropping below 0.5 bar.
Probable Causes
Air vented from radiators without subsequent water replenishment.
Undetected leak in underfloor heating circuit or radiator thermostatic valves.
Clogged hydraulic sensor orifice blocking water pressure from reaching microswitch.
Diagnostic & Testing Steps
- •Display shows flashing E119 error code with spanner icon.
- •Central heating and domestic hot water production disabled.
- •Front panel analog manometer shows needle resting below 0.5 bar.
Tools & Equipment Required
- ✓Digital Multimeter (Continuity Test)Verify low water pressure microswitch continuity (0 Ω when pressurized above 0.5 bar).
- ✓Boiler Filling Loop Braided Hose & KeyOpen internal double check valve to repressurize sealed system to 1.2 bar.
- ✓Torx T20 & Slotted ScrewdriversLower electronic control housing to inspect pressure sensor wiring harness.
- ✓Radiator Air Vent Bleed KeyPurge trapped air pockets from upper radiators after repressurizing.
- ✓Microfiber TowelCatch small water drips when disconnecting flexible filling loop.
Fast Reset Sequence: Boiler Electronic Flame Lockout Reset
Before unmounting panels or beginning diagnostic procedures, attempt this manufacturer reset to clear transient microcomputer lockouts:
- 1.Locate the flame reset button (marked with 'R' or a flame icon with a cross line).
- 2.Press and hold the button for 3 to 5 seconds until the display flashes or burner light restarts.
- 3.Inspect boiler pressure gauge — water pressure must read between 1.0 and 1.5 bar for safe burner ignition.
- 1
Step 1: Check Pressure Gauge Needle in Red Zone
[ ] DoneInspect the analog pressure gauge on the lower boiler control panel. If the black needle has fallen below 0.6 bar into the red sector, the low water pressure safety switch has locked out the burner.
Verification:Pressure indicator rests stably in green zone between 1.0 and 1.5 bar. - 2
Step 2: Re-pressurize via Tap to 1.2 Bar Normal
[ ] DoneLocate the green Easy-Fill spring-loaded filling lever or braided filling loop beneath the boiler. Pull lever down gently to admit cold mains water until the gauge needle rises into the green band between 1.2 and 1.5 bar, then release lever immediately.
Verification:Switch reads 0.1–0.4 Ω with system pressurized; infinite resistance (OL) when depressurized. - 3
Step 3: Test Pressure Switch & Turn Selector to R
[ ] DoneTurn selector knob to Reset position for 2 seconds. Trigger room thermostat demand and verify pump run.
Verification:E119 clears immediately and boiler modulates burner to satisfy heat call.
Repair Solutions
Turn blue filling loop handles under the boiler until pressure reaches 1.2 bar.
Check pressure sensor electrical harness continuity (< 1.0 Ω across closed contacts).
Bleed air from radiator circuits and confirm stable needle position.
Frequently Asked Questions
Does Baxi E119 clear automatically once repressurized?
On most modern Baxi 600/800 models, E119 automatically clears as soon as system pressure rises above 0.8 bar without needing a manual reset.
What is the ideal cold operating pressure for Baxi combi boilers?
The manufacturer recommended cold pressure is 1.0 to 1.2 bar, rising to around 1.8–2.0 bar when radiators reach operating temperature.