- Boilers
- Gas boiler
E20
Baxi E20 on a gas boiler: heating flow NTC sensor faulty
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
Baxi E20 means the flow NTC sensor is faulty. It is not a reset code: note when it appears, photograph the information menu and call the authorised service centre. The technician checks the sensor and its wiring.
Safety first
Stop and check this first
- If you smell gas: Baxi says to switch the boiler off, not to operate any electrical device or switch on lights, to put out any flame and open the windows. Then leave the home and call your gas distributor's emergency number and the service centre from outside.
- Do not open the boiler to move cables or connectors: Baxi says to disconnect the power before any work and only qualified technicians may work on the appliance.
Safe checks you can perform
- Smell of gas or combustion fumes
- What Baxi says to do for 20
- Secondary code and reading in the information menu
- Sensor and wiring checked by the technician
Leave these tasks to a qualified professional
- Do not attempt this professional task: Flow NTC sensor measurement
- Do not attempt this professional task: Wiring continuity and insulation
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 sensor measurement
What they doThe technician measures the sensor resistance with a multimeter and compares it with the Baxi reference, about 10 kΩ cold at 25 °C, allowing for the actual water temperature.
They must show youthe value measured against the manufacturer's specification and the temperature it was measured at.
In writingthe value and the decision taken.
Wiring continuity and insulation
What they doThe technician checks the continuity of the sensor cable to the board and that there is no short circuit or damaged connector.
They must show youthe cable section or connector checked, with a photo.
In writingwhether the cable was repaired or the sensor replaced, with its part number.
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.
Smell of gas or combustion fumes
- Who:
- you.
- How:
- first, check whether there is a smell of gas or combustion fumes near the boiler, or whether anyone has a headache, dizziness or nausea.
- Result that matters:
- whether it is safe to carry on with the checks for 20.
- If you smell gas:
- do not touch the boiler; follow the gas warning and call from outside.
- If you smell fumes:
- switch the boiler off, open doors and windows and call the service centre, as Baxi says.
- Evidence to keep:
- a note of the time and what you noticed.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457
What Baxi says to do for 20
- Who:
- you.
- How:
- in the user table, 20 has no reset: Baxi says to call the authorised service centre. Do not press reset again and again or cut the power to test it.
- Result that matters:
- not wasting time on resets that do not apply to this code.
- If the code stays on the display:
- note the date and time and call the service centre.
- If it clears by itself:
- note it anyway; if it repeats, Baxi says to contact the service centre.
- Evidence to keep:
- photo of the display with the code and the time.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457
Secondary code and reading in the information menu
- Who:
- you.
- How:
- press the information key for at least 1 second and find line 00, internal secondary fault code, and line 01, heating flow temperature. Leave with the off and reset key.
- Result that matters:
- having the data that goes with 20 for the technician.
- If the reading on line 01 looks impossible or never changes:
- tell the technician, it points to the sensor or its cable.
- If you cannot read it:
- do not change any parameter; a photo of the code is enough.
- Evidence to keep:
- photo of lines 00 and 01 of the menu.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457
Sensor and wiring checked by the technician
- Who:
- Baxi authorised service centre.
- How:
- measures the flow sensor resistance, checks the wiring continuity and that there is no short circuit.
- Result that matters:
- whether the sensor or the cable is at fault.
- If the cable is broken or shorted:
- the wiring is repaired and the sensor is kept.
- If the cable is fine and the sensor does not follow the reference:
- the sensor is replaced.
- Evidence to keep:
- job sheet with the measured value and what was repaired.
Baxi says to disconnect the power before any work and only qualified technicians may work on the appliance. Sensors, internal wiring and the board are technician only.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457 · Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de instalación, montaje y funcionamiento para el instalador 7731458
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
- Baxi
- Product type
- Gas boiler
Known code variants
- 20
- AEG E20 error
- AEG Fehler E20
- AEG lavadora C2
- AEG lavadora E20
- AEG lavadora E21
- AEG lavatrice C2
- AEG lavatrice E20
- AEG lavatrice E21
- AEG lave-linge C2
- AEG lave-linge E20
- AEG lave-linge E21
- AEG Waschmaschine C2
- AEG Waschmaschine E20
- AEG Waschmaschine E21
- AEG washer C2
- AEG washer E20
- AEG washer E21
- aerotermia Viessmann E20
- Baxi 20
- Baxi E 20
- Bosch dishwasher E20
- Bosch E20
- Bosch E20 error
- C2
- code erreur AEG E20
- E20
- E20 AEG lavadora
- E20 AEG lavatrice
- E20 AEG lave-linge
- E20 AEG Waschmaschine
- E20 AEG washer
- E20 Bosch dishwasher
- E20 lavavajillas Bosch
- E21
- E22
- E23
- E24
- E:20
- Electrolux dryer E20
- Electrolux dryer E20 drain
- Electrolux E20 error tumble dryer
- Electrolux E20 lavadora
- Electrolux E20 secadora
- Electrolux washer 2 beeps
- Electrolux washer error E20
- Electrolux washer not draining
- Electrolux washing machine E20
- Error 20 Baxi
- error AEG E20
- error E20 Bosch
- error E20 lavadora Electrolux
- error E20 lavadora Zanussi
- error E20 secadora Electrolux
- error E20 secadora Zanussi
- errore AEG E20
- lavadora Electrolux 2 pitidos
- lavadora Electrolux no desagua
- lavadora Zanussi E20 no desagua
- lavavajillas Bosch E20
- Neodens Plus 20
- secadora Electrolux E20 desagüe
- secadora Zanussi 2 pitidos
- Viessmann E20
- Viessmann Vitocal 100-AW E20
- Vitocal 100-AW AM2V E20
- Vitocal E20
- Vitocal exhaust temperature overprotection
- Vitocal temperatura descarga E20
- Zanussi dryer 2 beeps
- Zanussi dryer C2
- Zanussi dryer E20
- Zanussi E20 error washer
- Zanussi E20 lavadora
- Zanussi secadora C2
- Zanussi secadora E20
- Zanussi tumble dryer error E20
- Zanussi washer E20 not draining
- Zanussi washing machine E20
What it means
On the Neodens Plus ECO, code 20 is flow NTC sensor faulty. The boiler uses this sensor to read the temperature of the water leaving for the heating. For 20, Baxi tells the technician to check the sensor, the continuity of the sensor wiring and that the wiring is not short circuited, and gives a reference of about 10 kΩ cold at 25 °C, a value that falls as temperature rises. The code does not say whether the sensor, a broken cable or a shorted cable is at fault.
Warnings and stop conditions
- Criticaleditorial warning
If you smell gas: Baxi says to switch the boiler off, not to operate any electrical device or switch on lights, to put out any flame and open the windows. Then leave the home and call your gas distributor's emergency number and the service centre from outside.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457
- Mediumsource verified
Do not open the boiler to move cables or connectors: Baxi says to disconnect the power before any work and only qualified technicians may work on the appliance.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de funcionamiento y mantenimiento para el usuario 7731457
Symptoms and causes
Probable causes · in order
- Flow NTC sensor faultyPossible
Baxi says to check the sensor. If its resistance does not follow the manufacturer reference while the cable is sound, the sensor is the cause.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de instalación, montaje y funcionamiento para el instalador 7731458
- Sensor wiring brokenPossible
A loose or corroded connector or a cut cable leaves the circuit open. A continuity test of the wiring separates it from the sensor.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de instalación, montaje y funcionamiento para el instalador 7731458
- Wiring short circuitedPossible
Baxi says to check that the wiring is not short circuited. A bare or pinched cable gives an impossible reading even with a good sensor.
Evidence: Baxi Neodens Plus 24/24 F ECO, 28/28 F ECO y 33/33 F ECO, instrucciones de instalación, montaje y funcionamiento para el instalador 7731458
Virtual technician
Does E20 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
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