Short answer
Baxi Neodens iPlus faults
Identify the code and check the version of your boiler.
Models and version of the manual
24/24 F, 28/28 F and 33/33 F. This guide corresponds to iPlus. The codes from Neodens Plus ECO do not transfer to this generation.
Consulted edition: 7861627-05 · 13/03/2025 · manufacturer's manualThe control options, accessories, and versions may limit which notifications appear in each installation.
Locate the code on your screen.
These accesses lead to their entry in the table. They are not a classification of the most common faults: the manual does not provide incidence statistics.
- A02.06
Low pressure in the heating circuit
- H02.07
Low pressure in the heating circuit (water filling required).
- H01.18
There is no water circulation (temporarily).
- E01.17
There is no water circulation (permanent).
- E04.10
The burner has not ignited after five attempts.
- E04.29
Maximum allowed number of resets reached
What to do without opening the boiler
- Note what you see.
Complete code, message, and pressure displayed by the equipment. Indicate whether it occurs when opening hot water, requesting heating, or in both cases.
- Identify the device.
Take a photo of the screen and the identification accessible without disassembling anything. Brand, model, and version help avoid confusing tables from different ranges.
- Describe how it started.
Determine whether the fault is continuous or intermittent and if there was a supply interruption or a recent intervention. If it reappears after a reset allowed by the user manual, do not chain resets.
Do not open the casing or manipulate gas, wiring, combustion, or flue gas outlet. If you smell gas, avoid flames and switches, leave the area, and notify the distributor's emergency service from a safe location; in case of immediate danger, call 112.
Baxi Neodens iPlus components Manufacturer's diagram
Documented codes table
The meaning of the warning is provided, not the repair operations reserved for qualified personnel. When the manufacturer groups several codes, the grouping is maintained; it is not interpreted as a range of numbers.
| Code | What does it indicate? |
|---|---|
| A00.34 | External sensor missing |
| A02.06 | Low pressure in the heating circuit |
| A02.18 | Incorrect configuration |
| A02.33 | Maximum filling duration fault exceeded |
| A02.34 | For automatic filling, the minimum interval time between the two requests was not reached. |
| A02.36 | Functional device disconnected |
| A02.37 | Disconnected passive functional device |
| A02.45 | Connection error |
| A02.46 | Device priority error |
| A02.48 | Error in the unit's operating configuration. |
| A02.49 | Node initiation fault |
| A02.55 | The serial number is missing or incorrect. |
| A02.76 | Internal memory reserved for complete customization of settings. No further changes can be made. |
| A02.80 | No termination resistor on the bus |
| A05.29 | Gas pressure below the limit |
| A05.30 | Gas pressure check fault |
| A05.95 | A brief flame interruption signal has been detected. |
| A08.02 | Shower elapsed time error |
| H00.42 | Open/defective pressure sensor or pressure too high |
| H00.81 | Ambient temperature sensor missing |
| H01.00 | Temporary communication error in the PCB |
| H01.05 | The maximum temperature difference between the inlet and the return has been reached. |
| H01.08 | Increase in supply temperature in the heating system, too fast |
| H01.14 | The maximum value of the supply or return temperature has been reached. |
| H01.18 | There is no water circulation (temporarily). |
| H01.21 | Too rapid an increase in the supply temperature during operation as domestic hot water. |
| H02.00 | Reset in progress. |
| H02.02 | Waiting for the introduction of configuration adjustments (CN1, CN2) |
| H02.03 | The configuration settings (CN1, CN2) have not been entered correctly. |
| H02.04 | The settings of the main PCB cannot be read. |
| H02.05 | Memory adjustment not compatible with the boiler's PCI type. |
| H02.07 | Low pressure in the heating circuit (water filling required). |
| H02.12 | Fault in the RL lockout input (discharge) of the boiler |
| H02.31 | The device requires an automatic filling of the system due to low pressure. |
| H02.38 | Maximum number of automatic filling cycles reached |
| H02.70 | Error during the test of the external heat recovery unit |
| H03.00 | There is no identification data for the boiler safety device. |
| H03.01 | Communication failure in the comfort software (internal fault in the PCB of the boiler) |
| H03.02 | Temporary flame loss |
| H03.05 | Internal stop |
| H03.08 | False flame |
| H03.09 | Low voltage |
| H03.17 | Gas control system fault |
| H03.26 | Boiler calibration request |
| H03.28 | Synchronization fault |
| H03.31 | Blocked flue error |
| H03.54 | Unknown fault |
| H20.36 | Manual calibration error |
| H20.39 | Without primary calibration |
| H20.40 | No gas configuration |
| E00.04 | Return temperature sensor not connected to the boiler ignition (when the boiler is turned on, the PCB detects if the sensor is present and connected) |
| E00.05 | Short circuit in the return temperature sensor |
| E00.06 | The return sensor is not connected during the operation of the boiler (the PCB has detected that the sensor has been disconnected during operation). |
| E00.07 | Return temperature sensor temperature too high |
| E00.16 | Domestic hot water accumulator temperature sensor not connected |
| E00.17 | Short circuit in the temperature sensor of the domestic hot water accumulator. |
| E00.40 | Water pressure sensor inlet open |
| E00.41 | Water pressure sensor input closed |
| E00.44 | Open DHW sensor |
| E00.45 | Short circuit in the DHW sensor |
| E01.12 | Return temperature measured by the sensor is higher than the supply temperature. |
| E01.17 | There is no water circulation (permanent). |
| E01.20 | The combustion gas has reached the maximum temperature. |
| E02.15 | Minimum time for the recognition of the central storage unit key exceeded |
| E02.17 | Permanent communication error on the PCB. |
| E02.32 | Time elapsed for automatic filling |
| E02.35 | Critical safety device disconnected |
| E02.39 | Insufficient pressure increase after automatic filling |
| E02.47 | The connection to an external device has failed. |
| E04.00 | Security configuration fault |
| E04.01 | Short circuit in the flow temperature sensor |
| E04.02 | Flow temperature sensor disconnected |
| E04.03 | The maximum supply temperature has been exceeded. |
| E04.04 | Short circuit in the combustion gas sensor |
| E04.05 | The combustion gas sensor has been disconnected. |
| E04.06 | The combustion gas has reached a critical temperature. |
| E04.07 | The maximum difference between the supply temperatures has been reached. |
| E04.10 | The burner has not ignited after five attempts. |
| E04.11 | Gas valve VPS test failed |
| E04.12 | Ignition failure due to a false flame detection |
| E04.13 | Fan blade blocked |
| E04.14 | Combustion fault |
| E04.15 | Fault due to exhaust gas blockage |
| E04.17 | Fault in the control circuit of the gas valve |
| E04.18 | The supply temperature is below the minimum. |
| E04.23 | Internal communication blockage |
| E04.24 | Gas family error not found |
| E04.25 | Flame loss error during safety time |
| E04.26 | Ignition fault |
| E04.27 | Gas valve open fault with flame detection |
| E04.28 | Gas valve information fault |
| E04.29 | Maximum allowed number of resets reached |
| E04.50 | Faulty gas valve |
| E04.54 | Unknown fault |
No matches found. Please check the code and the version of the equipment.
Is there a problem, but no fault code appears?
The absence of a warning does not rule out a fault. For a boiler that does not heat, does not deliver hot water, loses pressure, or operates intermittently, describe the symptom and the moment it occurs. Do not assume that the PCB, the pump, or a sensor is faulty without checking the equipment and the installation.
Request a review of the boiler. · Consult maintenance
Before requesting a repair
Does the code identify the spare part I need to buy?
No. A single warning can have multiple causes. The spare part reference requires identifying the appliance and confirming the fault; the code or a generic photograph is not sufficient.
Can it be reset again if the fault returns?
It is not advisable to chain resets. Follow only what is outlined for the user in your version's manual. A persistent or recurring lockout requires inspection.
When does it make sense to compare a new boiler?
When you have a diagnosis and a budget, compare repair, availability of the spare part, and replacement according to your installation. An isolated fault code does not justify changing the equipment.
Models of this guide in the catalog
See new boilers · Consult installation or replacement
The technical sheet of each product provides information on its price and availability. Installation is quoted separately depending on the case.
Does the warning still appear on your Baxi boiler? Consult the Baxi boiler technical service in Madrid or the spare parts and assistance for Baxi Roca.
Documentation and other guides
Consult fault guides by brand and model. · Return to the blog