Warmflow Agentis External Fault codes & diagnostics

14 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

CombiSystemHeat Only Oil 2018-present
Download the Warmflow Agentis External manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 11 High 2 Medium
Just want the most common Warmflow Agentis External faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 14 documented codes

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E01

Your boiler's burner has shut down because it cannot light the fuel, likely due to an empty oil tank or a blockage in the supply line.

High DIY-safe £100-250

What to check first

  1. Check your oil tank level to ensure you have not run out of fuel.
  2. Inspect the oil supply valves to ensure they are fully open.
  3. Locate and press the illuminated reset button on the burner unit within the external cabinet.

Parts commonly replaced

  • Oil pump
  • Photocell
  • Oil nozzle
  • Fuel filter

Related codes

Full explanation for E01
E02

Your boiler has switched itself off because it has detected that the water inside has become too hot.

High Engineer only £100-250

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Thermistor

Related codes

Full explanation for E02
E04

Your boiler has detected that the water pressure is too low for it to operate safely, which often happens after bleeding radiators or if there is a small leak.

High DIY-safe £80-160

What to check first

  1. Locate the filling loop (the flexible silver hose) underneath or near the boiler.
  2. Slowly open the valve(s) until you hear water flowing and the pressure gauge rises to between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly and restart the boiler to clear the fault.

Parts commonly replaced

  • Expansion vessel
  • Pressure relief valve
  • Automatic air vent

Related codes

Full explanation for E04
E05

Your boiler has lost connection with a internal temperature sensor, meaning it cannot safely tell how hot the water is and has shut down as a precaution.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Temperature Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for E05
E06

Your boiler has detected a problem with the sensor that monitors the temperature of your hot water, meaning the system cannot safely heat water for your taps.

High Engineer only £90-160

Parts commonly replaced

  • DHW Flow NTC Sensor
  • Wiring harness connector

Related codes

Full explanation for E06
E11

Your boiler's internal temperature sensor has slipped out of its correct position or is sending an unusual reading, meaning the system cannot safely monitor the water tank temperature.

Medium Engineer only £90-160

Parts commonly replaced

  • NTC Temperature Sensor Probe
  • Sensor Retaining clip

Related codes

Full explanation for E11
E12

Your boiler has lost communication with the temperature sensor that monitors your hot water tank, meaning it cannot safely heat your water.

High Engineer only £120-190

Parts commonly replaced

  • Tank Control NTC Sensor
  • Sensor Wiring Harness

Related codes

Full explanation for E12
E15

Your boiler's internal sensor that monitors the water returning from your radiators has developed a fault or become disconnected.

Medium Engineer only £90-160

Parts commonly replaced

  • CH Return NTC Thermistor
  • Sensor Wiring Harness

Related codes

Full explanation for E15
E22

Your boiler's internal computer brain has suffered a memory error and can no longer process instructions safely.

High Engineer only £250-£450

Parts commonly replaced

  • Main PCB (Printed Circuit Board)

Related codes

Full explanation for E22
E31

Your boiler has lost its connection to the external control panel, meaning it cannot receive the signals it needs to turn on or off.

High Engineer only £90-250

Parts commonly replaced

  • Remote control wiring
  • Digital control interface
  • Main PCB

Related codes

Full explanation for E31
E32

Your boiler's main control panel is having trouble communicating with the internal computer, likely due to a wiring issue or a faulty circuit board.

High Engineer only £180-450

Parts commonly replaced

  • Main Control PCB
  • MMI Display Unit
  • Communication Cable

Related codes

Full explanation for E32
E46

Your boiler has lost its connection to the sensor that monitors water pressure, meaning it cannot confirm if it is safe to operate.

High Engineer only £120-220

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness
  • Main PCB

Related codes

Full explanation for E46
E48

Your boiler has detected too much water pressure in the system, which can cause the safety valve to leak if left unaddressed.

Emergency DIY-safe £0-120

What to check first

  1. Check that the silver braided filling loop valves are tightly closed.
  2. Locate a radiator and use a bleed key to release water into a cloth until the pressure gauge drops to 1.5 bar.
  3. Reset the boiler to clear the fault code.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for E48
E62

Your boiler's main internal computer and the display panel are having trouble communicating, which has caused the system to stop working for safety.

High Engineer only £250-£550

Parts commonly replaced

  • Main Control PCB
  • MMI Display Board
  • PCB Wiring Harness

Related codes

Full explanation for E62
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