- Boilers
- Gas boiler
E2
Junkers E2 on a gas boiler: flow temperature sensor fault
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Junkers E2 means the boiler reads the heating flow temperature sensor as faulty. Without that reading the boiler cannot regulate. Reset once and, if it stays, call the service centre.
Safety first
Stop and check this first
- Bosch states the customer must not modify or repair the appliance and recommends an annual maintenance contract with an official service centre.
Safe checks you can perform
- Reset or power cycle
- Model and appliance details
- Flow sensor measurement
Leave these tasks to a qualified professional
- Do not attempt this professional task: Flow NTC measurement
- Do not attempt this professional task: Heating test after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Flow NTC measurement
What they doThe technician measures the flow sensor resistance with a multimeter against the manufacturer's curve and checks the cable.
They must show youthe measured value against the curve.
In writingwhat was measured and what was replaced.
Heating test after the repair
What they doAfter the repair, the technician runs the heating and checks the flow temperature rises and settles without E2.
They must show youthe flow temperature on the display.
In writingthe date and result.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Reset or power cycle
- Who:
- you.
- How:
- if the reset key is flashing, hold it; otherwise switch the boiler off and on, as Bosch says.
- Result that matters:
- whether E2 clears and the boiler shows a flow temperature.
- If it clears and does not return:
- note the date.
- If E2 returns:
- call the official service centre with the code and appliance details.
- Evidence to keep:
- a photo of the display with E2.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Model and appliance details
- Who:
- you.
- How:
- note the model and the rating plate details before calling; Bosch asks for the fault and appliance details.
- Result that matters:
- having the exact model so the technician brings the right sensor.
- If you have the model:
- the technician can come prepared.
- If you cannot find it:
- take a general photo of the boiler.
- Evidence to keep:
- a photo of the rating plate.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Flow sensor measurement
- Who:
- official service technician.
- How:
- measures the flow sensor and its cable continuity.
- Result that matters:
- whether the sensor is within its curve and the cable is not open.
- If the sensor is off the curve:
- that confirms the sensor.
- If it measures fine:
- it points to the cable or connector.
- Evidence to keep:
- a report with the measured values.
The sensor is in the boiler circuit, next to mains voltage and gas: the technician measures it.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Boilers
- Brand
- Junkers
- Product type
- Gas boiler
Known code variants
- Bosch E2 caldera
- Candy 2 flashes
- Candy 2 parpadeos
- Candy dishwasher 2 flashes
- Candy dishwasher E2
- Candy dishwasher error E2
- Candy dishwasher not filling with water
- Candy lavadora E2
- Candy lavavajillas E2
- Candy washer E2
- Candy washer not filling
- Candy washing machine error E2
- Cerapur E2
- CHECK WATER
- COMPROBAR AGUA
- De'Longhi dehumidifier E2 E3 sensor
- De'Longhi E2
- De'Longhi E3
- DeLonghi DD230P E2
- deshumidificador De'Longhi E2 E3 sensor
- deshumidificador Meaco E2 sensor de humedad
- E02
- E-2
- E2 Worcester
- E3
- error E2 frigorífico Indesit
- Error E2 Junkers
- error E2 lavadora Candy
- error E2 lavadora Samsung
- error E2 lavavajillas Candy
- error E2 lavavajillas Haier
- frigorífico combi Indesit E2 sensor
- Greenstar E2
- Haier dishwasher E2
- Haier dishwasher error E2
- Haier dishwasher not filling
- Haier E2
- Haier lavavajillas E2
- Indesit E2 error fridge freezer
- Indesit E2 frigorífico
- Indesit fridge freezer E2
- Indesit fridge freezer E2 sensor fault
- Junkers E2
- lavadora Candy no coge agua
- lavadora Samsung E2 agua en el tambor
- lavadora Samsung no desagua E2
- lavavajillas Candy 2 parpadeos
- lavavajillas Candy no coge agua
- lavavajillas Haier no coge agua
- Meaco dehumidifier E2 humidity sensor
- Meaco E2
- MeacoDry Arete E2
- NO WATER
- Samsung E2 desagüe
- Samsung E2 drain error
- Samsung E2 water left in drum
- Samsung lavadora E2
- Samsung washer error E2
- Samsung washer not draining E2
- Samsung washing machine E2
- Worcester boiler E2 fault
- Worcester Bosch E2
- Worcester E2
What it means
On the CerapurComfort, E2 is "flow temperature sensor defective", and Bosch says to check the sensor and its cable. On the ZWE, the same code is an open flow NTC. The flow sensor measures the water going out to the radiators and the control uses it to modulate the burner; with an impossible reading it cannot regulate. The sensor, cable or connector can fail. The code does not tell them apart.
Warnings and stop conditions
- Mediumsource verified
Bosch states the customer must not modify or repair the appliance and recommends an annual maintenance contract with an official service centre.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Symptoms and causes
Probable causes · in order
- Damaged flow sensorCommon
Bosch names the sensor. If it measures off its curve with a good cable, it is the cause.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
- Sensor cable or connectorPossible
Bosch asks for the connecting cable to be checked; a break or loose connector gives the same impossible reading.
Evidence: Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico · Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Virtual technician
Does E2 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
Junkers CerapurComfort ZWBC 25-2 C, instrucciones de instalación y manejo para el técnico
Junkers (Bosch Termotecnia) · 2012 · manual
- 2
Junkers ZWE 24-3 y 28-3 H A con Bosch Heatronic, instrucciones de instalación
Junkers (Bosch Termotecnia) · 2000 · manual
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