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Vaillant

TurboMax Pro 28E

Combi Boiler 28kW 2005-2013 ErP B 99 fault codes

<p>The TurboMax Pro 28E is a combi boiler from Vaillant, available at 28kW output. Produced 2005-2013.</p>

TurboMax Pro 28E Fault Codes 99

Code Description Severity Type
F.00 Flow Temperature Sensor Interruption The flow NTC (Negative Temperature Coefficient) sensor has an open circuit or broken connection. The sensor… High Engineer View Guide
F.01 Return Temperature Sensor Interruption The return NTC temperature sensor has a faulty connection or open circuit. The return sensor monitors… High Engineer View Guide
F.05 Outside Temperature Sensor Break The outdoor NTC temperature sensor cable is broken or disconnected. The boiler cannot read the external… Medium Engineer View Guide
F.06 Outside Temperature Sensor Short Circuit The outdoor NTC temperature sensor has a short circuit. This prevents weather-compensated heating from working correctly. Medium Engineer View Guide
F.10 Flow NTC Short Circuit The flow temperature sensor has developed a short circuit. This prevents the boiler from accurately reading… High Engineer View Guide
F.11 Return NTC Short Circuit The return temperature sensor has short-circuited. The boiler cannot monitor return water temperature and has locked… High Engineer View Guide
F.12 DHW Sensor Short Circuit The domestic hot water temperature sensor has short-circuited. On combi boilers this prevents the boiler from… Medium Engineer View Guide
F.13 Cylinder Temperature Sensor Short Circuit The cylinder (store) temperature sensor has short-circuited. Relevant on system boilers paired with a cylinder. Medium Engineer View Guide
F.17 Outside Temperature Sensor Short Circuit The outside temperature sensor (used for weather compensation) has short-circuited. Does not prevent heating but disables… Low Engineer View Guide
F.19 eBUS Subscriber Voltage Too High The voltage on the eBUS data communication line is higher than expected, often caused by a… Medium Engineer View Guide
F.20 Safety Overheat Lockout The boiler has reached an unsafe temperature and the safety thermostat has triggered. This can be… High Engineer View Guide
F.22 Low Water Pressure System water pressure has dropped below the safe minimum level. This is one of the most… Low DIY View Guide
F.23 Temperature Spread Too High The temperature difference between the flow and return water is too large. This usually indicates poor… Medium Engineer View Guide
F.24 Flow Temperature Rising Too Fast The boiler flow temperature is increasing too quickly, suggesting insufficient water flow past the heat exchanger.… Medium Engineer View Guide
F.25 Flue Gas Temperature Too High The temperature of combustion gases in the flue has exceeded safe limits. This can indicate a… High Engineer View Guide
F.26 Gas Valve Error The gas valve has a fault and may not be functioning correctly. This is a safety-critical… High Engineer View Guide
F.27 Flame Simulation / Safety Lockout The boiler has detected a flame signal when there should be none, triggering a safety lockout.… High Engineer View Guide
F.28 Ignition Failure / No Flame Detected The boiler has failed to light after multiple ignition attempts. One of the most common faults,… Medium DIY View Guide
F.29 Flame Loss During Operation The boiler successfully ignited but then lost the flame during operation. Usually caused by gas pressure… Medium DIY View Guide
F.32 Fan Error The boiler fan is not reaching the required speed for safe ignition, or the fan speed… High Engineer View Guide
F.33 VR40 Relay Switch-Off After 24 Hours The relay in the gas valve has not switched after 24 hours. This is a safety… Medium Engineer View Guide
F.35 Flue/Air Supply Issue A fault has been detected with the flue gas path or air supply. The boiler cannot… High Engineer View Guide
F.36 Flue Gas Sensor Short Circuit The flue gas temperature sensor has short-circuited. High Engineer View Guide
F.41 Fan Speed Out of Range (Too High) The boiler fan is running faster than its maximum rated speed, indicating a fault with the… High Engineer View Guide
F.42 Coding Resistor / Gas Valve Fault The coding resistor for the gas valve is giving an incorrect signal, or the gas valve… High Engineer View Guide
F.46 Phase / Neutral Fault The boiler has detected that the live and neutral connections are reversed. This is an electrical… High Engineer View Guide
F.47 Short Circuit / Low Voltage on Ionisation The ionisation sensing electrode is detecting a short circuit or the voltage is too low. The… High Engineer View Guide
F.49 eBUS Communication Error There is a communication fault on the eBUS — the data bus that allows the boiler… Medium Engineer View Guide
F.52 Mass Flow Sensor Connection Fault The mass flow sensor is not connected or is disconnected. The plug may not be connected… High Engineer View Guide
F.53 DHW Flow Rate Too High The domestic hot water flow rate through the boiler is too high, preventing the water from… Medium Engineer View Guide
F.54 Gas Pressure Too Low The gas supply pressure to the boiler is below the minimum required for safe operation. Can… High Engineer View Guide
F.55 Burner Control Module Fault The burner control module has detected an internal fault. High Engineer View Guide
F.56 Mass Flow Sensor Regulation Fault The gas valve or its cable harness is defective, causing the mass flow sensor to give… High Engineer View Guide
F.57 Comfort Mode Heat Demand Not Met The boiler is running in comfort (reduced loss) mode but cannot meet the heat demand. Low DIY View Guide
F.60 Gas Valve Control Fault (Older Models) On older Vaillant models (turboMAX Plus, ecoMAX), F.60 indicates a cable loom or gas valve assembly… High Engineer View Guide
F.61 Gas Valve Regulation Error The gas valve has an electronic fault affecting how it regulates gas flow. This is a… High Engineer View Guide
F.62 Gas Valve Closure Delay Error The gas valve is taking too long to close after the boiler shuts down, indicating a… High Engineer View Guide
F.63 EEPROM Error There is an internal electronic memory (EEPROM) fault on the PCB. The boiler's control board cannot… High Engineer View Guide
F.64 Electronics / NTC Fault A short circuit has been detected involving either the flow or return NTC sensor, or there… High Engineer View Guide
F.65 Electronics Temperature Too High The temperature of the electronics/PCB itself is too high. This can be caused by an external… High Engineer View Guide
F.67 Electronics Flame Signal Error The PCB is receiving an unexpected or erroneous flame signal. This indicates a fault with the… High Engineer View Guide
F.68 Unstable Flame / Air in Gas The boiler flame is unstable, often caused by air in the gas supply, a partially blocked… High Engineer View Guide
F.70 Invalid Device Specific Number (DSN) The boiler has an invalid or unrecognised device-specific configuration number. Usually occurs after PCB replacement if… Medium Engineer View Guide
F.71 Flow Temperature Sensor Constant Value The flow temperature sensor is sending a fixed, constant reading rather than a variable one, suggesting… Medium Engineer View Guide
F.72 Flow/Return Temperature Difference Too Great The temperature difference between the flow and return sensors exceeds safe limits. Can indicate a sensor… Medium Engineer View Guide
F.73 Water Pressure Sensor Signal Too Low The pressure sensor is reading below its expected operating range. This could mean the sensor itself… High Engineer View Guide
F.74 Water Pressure Sensor Signal Too High The pressure sensor is reading above its expected operating range. Usually indicates a faulty sensor, or… High Engineer View Guide
F.75 Pump / Pressure Sensor Fault The boiler cannot detect a pressure change when the pump starts. This is the most common… Medium DIY View Guide
F.76 Primary Heat Exchanger Overheating The overheating protection on the primary heat exchanger has activated. Often caused by scale buildup, low… High Engineer View Guide
F.77 Flue Non-Return Flap / Condensate Pump Error The condensate pump or flue non-return flap is not operating correctly. More common on boilers with… Medium Engineer View Guide
F.78 DHW Outlet Sensor Interruption There is an interruption to the domestic hot water outlet sensor when connected to an external… Medium Engineer View Guide
F.83 Flow/Return Temperature Sensor Error Both the flow and return temperature sensors are reading incorrectly or giving impossible readings. High Engineer View Guide
F.84 Flow and Return Sensors Exchanged The flow and return temperature sensors appear to be reading the wrong values, suggesting they have… High Engineer View Guide
F.85 Temperature Sensors Incorrectly Fitted The flow and return temperature sensors appear to be fitted the wrong way around, giving inverted… Medium Engineer View Guide
F.90 Water Flow Rate Too Low Insufficient water flow through the primary heat exchanger — caused by an airlocked or undersized pump,… Medium Engineer View Guide
F.92 Coding Resistor Fault The coding resistor on the PCB does not match the entered gas family. The boiler cannot… High Engineer View Guide
F.93 Incorrect Parameter Settings The boiler has been configured with an incorrect setting — typically after a PCB replacement or… Medium Engineer View Guide
S.00 Temperature Too High (Blocking) A blocking (non-lockout) status code: flow temperature is too high. The boiler will wait until temperature… Medium Engineer View Guide
S.01 Water Pressure Below Minimum A status (non-lockout) code indicating system pressure is approaching the minimum. The boiler is blocking but… Low DIY View Guide
S.02 DHW Demand Active A status code showing the boiler is actively heating domestic hot water. Not a fault —… Low DIY View Guide
S.03 Heating Mode — Ignition Sequence Status code: The boiler is going through its ignition sequence. Normal operating status. Low DIY View Guide
S.04 Blocking: Return Sensor Too Hot The return temperature is too high — the boiler is in a blocking state and will… Medium Engineer View Guide
S.05 Status: No Heat or Hot Water Demand The boiler is in standby with no demand for heating or hot water. This is a… Medium DIY View Guide
S.06 Boiler in Heating Mode A status code showing the boiler is providing central heating. Not a fault. Low DIY View Guide
S.07 Fan Running After Shutdown (Aftercool) The fan continues to run for a short time after the burner has switched off to… Low DIY View Guide
S.08 DHW Off (Summer Mode) The boiler's domestic hot water supply has been switched off, usually via the user controls or… Low DIY View Guide
S.09 Status: Burner Off — Anti-Cycle The boiler burner is off due to an anti-cycling delay. This prevents the boiler from short-cycling… Medium DIY View Guide
S.10 Blocking: Anti-Cycle Control Active The anti-cycle timer is preventing the boiler from restarting immediately after a heating cycle. This is… Low DIY View Guide
S.11 DHW Mode — Fan Starting Status code: The fan is starting up for a domestic hot water cycle. Normal operating status. Low DIY View Guide
S.12 Status: Pump Over-Run After Heating The boiler has finished a heating cycle and the pump is running to dissipate residual heat.… Medium DIY View Guide
S.13 DHW Mode — Ignition Sequence Status code: The boiler is going through its ignition sequence for a domestic hot water cycle. Low DIY View Guide
S.14 DHW Mode — Burner Ignited Status code: The burner is ignited and domestic hot water heating is in progress. Low DIY View Guide
S.15 DHW Mode — Pump and Fan Overrun Status code: Both the pump and fan are running after a DHW cycle to cool the… Low DIY View Guide
S.16 DHW Mode — Fan Overrun Status code: The fan is running after a DHW cycle has ended to clear residual combustion… Low DIY View Guide
S.17 DHW Mode — Pump Overrun Status code: The pump is running after a DHW cycle to distribute heat from the heat… Low DIY View Guide
S.20 DHW Mode — Burner On Status code: The burner is firing in domestic hot water mode. Normal operating status. Low DIY View Guide
S.21 DHW Mode — Fan Starting Status code: Fan starting for domestic hot water cycle. Normal status. Low DIY View Guide
S.22 DHW Mode — Pump Running Status code: The pump is running for a domestic hot water cycle. Low DIY View Guide
S.23 DHW Mode — Ignition Sequence Active Status code: Ignition sequence for domestic hot water. Low DIY View Guide
S.24 DHW Mode — Burner Ignited Status code: Burner is lit for domestic hot water heating. Low DIY View Guide
S.25 DHW Mode — Fan and Pump Overrun Status code: Both fan and pump in overrun after DHW cycle. Low DIY View Guide
S.26 DHW Mode — Fan Overrun Status code: Fan overrun after DHW cycle. Low DIY View Guide
S.27 DHW Mode — Pump Overrun Status code: Pump overrun after DHW cycle. Low DIY View Guide
S.28 DHW Mode — Anti-Cycle Timer Status code: The boiler is in its anti-cycling period between hot water calls. Low DIY View Guide
S.30 Room Thermostat Blocking Heat Demand Status code: The external room thermostat is blocking heating mode — the room has reached the… Low DIY View Guide
S.31 Summer Mode — No Heat Demand Status code: The boiler is in summer mode (central heating switched off at controls or thermostat).… Low DIY View Guide
S.32 Fan Speed Variation — Waiting Period Status code: The boiler is in a waiting period due to fan speed deviation. The boiler… Medium Engineer View Guide
S.33 Status: Fan Running — Pre-Purge The fan is running to purge the combustion chamber before ignition. This is a normal pre-ignition… Medium DIY View Guide
S.34 Frost Protection Mode Active Status code: The boiler's frost protection function has activated. The boiler will fire briefly to prevent… Low DIY View Guide
S.36 Status: Boiler Firing for Heating Demand The burner is running to satisfy a central heating demand. This is normal operating status. Medium DIY View Guide
S.39 External Contact / Condensate Pump Blocking Status code: An external switching contact (such as a condensate pump float switch) is preventing burner… Medium Engineer View Guide
S.40 Flue Gas Recirculation Detected The boiler has detected that flue gases may be recirculating back into the air intake. This… High Engineer View Guide
S.41 System Pressure Too High (>2.8 bar) Status code: The system water pressure has exceeded 2.8 bar. The boiler is blocking for safety.… Medium Engineer View Guide
S.42 Domestic Hot Water Priority Active The boiler is prioritising domestic hot water demand and heating has been temporarily suspended. This is… Low DIY View Guide
S.46 Comfort Mode — Flame Loss at Minimum Load Status code: Flame lost at minimum burner output while in comfort mode. The boiler is blocking… Medium Engineer View Guide
S.53 Heat Demand Blocking (Anti-Cycle) The boiler has satisfied the heating demand and is in its anti-cycling period before it can… Low DIY View Guide
S.56 Status: Diverter Valve Active The diverter valve is switching to direct hot water to taps rather than radiators. Normal combi… Medium DIY View Guide
S.58 Noise Reduction Mode Active Status code: The boiler's modulation is being limited to reduce noise. This may occur due to… Low DIY View Guide
S.61 Gas Family Check Unsuccessful Status code: The boiler has run an automatic gas family check and the result was outside… Medium Engineer View Guide

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