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2024 Grant Boiler Error & Fault Codes


Every brand of boiler will have a series of problems and an error code to show for it. Grant boilers are well known in the industry as being one of the best easily identifiable brands on the market. Understanding your boiler and its error codes is crucial to maintaining your boilers performance level and preparing you for any problems or issues that may occur.

Error codes are system wide notifications that a problem has occurred within the Grant boiler or system. The error code will indicate where the fault lies within the boiler or system and grant will send out an engineer to take a look at it. The engineers at Grant are highly trained and they will identify the fault and resolve it in an efficient manner.

In this article we have listed all the possible error codes for Grant boilers and detailed what the fault is, what you can do yourself and what you need to call an engineer for.

General Grant Boiler Error Codes


When you get an 'Error Code' from Grants Boiler, you will need to know how to interpret the error code and then you will need to know how to correct the issue. It requires experimentation to find the right combination.

This list of error codes for a Grant boiler is aimed at providing troubleshooting information if you experience problems with your boiler. While it does not mean the problem will be easy to fix, it should give you some idea of where you might need to start looking.

Fault Code Possible Cause
No display12V transformer failure
PP1Inlet (return) water temperature sensor failure
PP1Inlet (return) water temperature sensor failure
PP2Discharge gas sensor failure
PP3Coil temperature sensor failure
PP4Return gas sensor failure
PP5Ambient temperature sensor failure
PP6Discharge gas overheat protection
PP7Winter anti-freeze protection in operation
EE1High pressure – circulating pump failure or circuit air locked
EE2Low pressure
EE3Open circuit between PCB terminals 23-24
EE4Supply L and N are reversed
EE8Communication failure
Flashing on and offDefrosting
E01Internal control fault
sHrHP flow sensor short / HP return sensor short
OPnHP flow sensor open / HP return sensor open
SUPSupply sensor short / Supply sensor open
OUTDROutdoor sensor short / Outdoor sensor open
C2849Fault C; Chassis Code
Problem is controller area network wiring bus and modules.
fault two; MFG – Manufacturer Specific
Fault eight; Ignition System Or Misfire
fault four; BBV Sensor Circuit Low Voltage
fault nine; Kick-Down Switch Failed Short
U2453Fault U: Network Code
Problem is climate control system, lighting, airbags, etc..
fault two; MFG – Manufacturer Specific
fault four; Transmission
fault five; TP Sensor Learn Not Complete
fault three; Transmission Control Module Reprogrammable Memory

Grant Boiler Error Descriptions


Boiler error codes will normally appear on your boiler's display or a remote programmer device connected to it. In addition to showing the error code, your boiler will usually tell you what it means too - check that you read this information correctly.

This is the list of Grant Boiler Error Codes from Service Manuals. This list might be useful if you are a service engineer, just remember these codes could be slightly different as they are by different boiler models.

Fault Code Possible Cause
Boiler Will Not StartLow pressure cut-out activated
No electrical supply to burner
Check controls are switched on and calling for heat
Boiler thermostat and/or overheat thermostat faulty
Burner lights but goes to lock-outFault with burner
No fuel supply
Oil tank empty
Fire valve closed
Fire valve closed
Fuel line filter is blocked
Oil supply line is air locked
Excessive combustion air
Fault with burner
Burner fires but smoke visible from flue or high smoke numberInsufficient combustion air supply to burner
Incorrect or faulty nozzle fitted
Fuel pressure too high
Burner pulsatesInsufficient combustion air supply to burner
Burner cycles On and OffContaminated combustion air (balanced flue)
Insufficient oil flow to burner due to restriction in supply line
Excessive combustion air
Fumes and puffing on startingFlue is blocked
Insufficient flue draught
Flue pipe or liner is too large or existing stack is unlined
Insufficient combustion air supply to burner
Flame slow to stabilise on startingInsufficient combustion air supply to burner
Fuel pressure too low
Oil smellsOil leak in supply line or burner
Combustion fume smellsLeak around boiler cleaning door
Burner not correctly fitted on mounting flange
Burner seal ‘O’ ring damaged or missing
Leakage around flue connection
Overheat thermostat operatingFaulty boiler thermostat
Thermostat sensor not connected to printed circuit board (PCB) – Vortex Combi only
Faulty overheat thermostat
No water flowing from hot tapMains water supply is not connected to cold water inlet of boiler
One or more isolating valves, stop cocks, etc. in the pipework are closed
The cold water isolating valve in the boiler is closed
There is a blockage (or blockages) in the pipework
No hot water operationHot tap is not connected to hot water outlet of boiler
Insufficient flow of water through boiler
Boiler cold water and hot water connections reversed
Thermostatic mixing valve incorrectly fitted
Pump is not operating in hot water mode
Diverter valve microswitch(es) faulty
Diverter valve microswitches not operated
Diverter valve seized
Diverter valve diaphragm failed
Low water temperature at tapFlow of water through boiler too high
Boiler thermostat incorrectly set
Thermostatic mixing valve incorrectly set
Faulty boiler thermostat
Pump speed setting too low
Pump is incorrectly fitted
Hot water for short period onlyBurner not firing for hot water (after a short time) Burner oil pressure set too low at oil pump
Incorrect oil nozzle fitted to burner
No operation on heatingTimeswitch either not set, or not in an ‘ON’ period
Timeswitch not operating
Faulty timeswitch
Faulty timeswitch switch contacts
Timeswitch OK but not switching boiler on
Heating switch set to ‘HOT WATER ONLY’
Room thermostat not calling for heat
Faulty room thermostat
No room thermostat or external timeswitch connected to boiler
Flow temperature lowBoiler thermostat is set too low
Boiler thermostat faulty
Boiler is underfired
Combustion setting of burner incorrect
Boiler heat exchanger is sooted up

Grant Vortex Blue Error Codes


The Grant Vortex Blue is a condensing boiler which runs off gas or oil and can be suited for homes of any size. It is known for the reliability of its design and the energy efficiency it incorporated. If you are having problems with your boiler getting stuck in the heating position, we have a list of the Grant Vortex Blue Error Codes that you can use to help you diagnose and repair this issue.

Fault Code Possible Cause
Red blinking lightPresence of a false flame signal before heat request
Red blinking lightPresence of false flame signal during pre-purging
Red blinking lightPresence of false flame signal during post-purging or pre-heating
Red steady onUV sensor defective or dirty oil valve defective fault – ignition transformer badly regulated burner, oil fuel not present
Red blinking lightBadly adjusted burner, oil valve defective or dirty UV sensor defective or dirty
Red and orange blinking invertedError with oil valve internal control circuit that drives the oil valve error
Red green blinking invertedInternal memory error
Orange green blinking invertedCheck presence of voltage, check the condition of the fuses, check that safety thermostat is not in lockout
OffEliminate the extraneous light
Check that plugs and sockets are connected properly
Red blinking lightEliminate the extraneous light
Red steady onClear it / replace it / check the pressure and output of the fuel / check air output change nozzle check the coil od solenoid valve
Green blinking lightSet the air according to the instructions of the manual or replace

Grant Vortex Eco Error Codes


So here is a list of Grant Vortex Eco Error Codes for your boiler. It can be useful to run through these systematically in order to find out what the problem is and how you might fix it. You may have to hit more than one of these issues before you manage to fix your problem.

Eco Error Codes are messages displayed on the Grant Vortex boiler display. If you get a message on your boiler, it's usually just one of these error codes. The table helps you to diagnose which part of the boiler is probably faulty and what method you should use for resetting it.

Fault Code Possible Cause
Motor fails to runNo electrical supply to boiler check on/off switch is on – it should be neon lit
Lock-out light not litFuse has blown – check reason for failure
Motor fails to runNo power to burner motor
Burner lock outBurner motor capacitor fault check and replace if necessary

Grant Vortex / Eco / Pro Boiler Error Codes


This is a list of Grant's Vortex, Eco and Pro boilers error codes. These are the most common error codes or fault codes that your boiler might display. Error codes are fed back from the boiler to control panels (like PC's) so they can be understood as text and displayed to the user.

Fault Code Possible Cause
No fuel supplyInsure that an adequate supply of fuel is available and that the fuel supply valve is open – check the condition of the fuel filter and clean if necessary, ensure fuel supply is reaching burner and vent pump
No Electricity SupplyEnsure electricity supply to the boiler is switched on and that all controls are calling for heat – ensure that the overheat thermostat has not tripped, reset if necessary and check the mains supply
Burner not starting – fuel and electricity supplies presentReset boiler on the burner control box – if it is lit refer to burner fault finding charts
Burner lights but goes to lock outIf the flame is unstable check the combustion setting
Visible smoke from flue or high smoke numberInsufficient air supply. Check the air damper setting and the condition of the fan check room ventilation, check the nozzle size and type, fuel pressure may be too high, check and adjust
Burner pulsesInsufficient air supply – check the air damper setting and the condition of the fan, check room ventilation
Flame slow to stabilise during start upInsufficient air supply – Check the nozzle size and type as fuel pressure may be too low, check and adjust insufficient draught clean boiler heat exchanger and check condition of flue
Water temperature lowUndersize nozzle and or low fuel pressure check condition of boiler heat exchanger and clean if necessary. Check the boiler thermostat, check the combustion setting, check the condition of the fuel filter
Boiler operating an overheat thermostatFaulty boiler thermostat – no circulation, check circulating pump, check for air lock
Fumes and puffing during startingCheck the condition of the chimney to ensure it is not blocked and is high enough to produce the required draught – check that there is an adequate air supply near the burner fan is not drawing products out of the burner
Oil odoursCheck all fuel line connections and remake as necessary
Combustion fumes smellCheck boiler cleaning cover and seal are correctly fitted, check burner is correctly fitted onto flange, check flue is correctly sealed into flue outlet of boiler, check the condensate pipe and trap are operating correctly

Grant Vortex Pro Combi Error Codes


The Grant Vortex Pro Combi will make an error code and display the error code icon on the programmer every time there is a fault. The errors that the programmer can potentially detect are displayed by the programmer in different colours so it's easy to tell what the cause of the problem is. This article outlines all of the potential error codes that can be generated by boiler programmer.

Fault Code Possible Cause
Power supplyCheck that fused spur for heating system and boiler is switched on – check that the electricity supply has not failed
Heating system controlsCheck that the timer or programmer is working and set to an on period
Boiler controlsCheck boiler on/off switch is set to on – check that power indicator on and control panel is lit
BurnerCheck the burner lockout reset button is lit, if yes press the reset button to start the burner if burner fails call an engineer
Heating systemCheck the heating system water pressure
PowerIf the boiler is not lit it could be a problem with power supply to the boiler switched off or possibly blown a fuse
DHW pumpIf flashing this indicates either a store thermistor or PCB fault
FlowIf the boiler is not lit when a hot tap is opened this could mean there is a lack of water flow or possible flow switch problem
DemandIf not lit this indicates either timer or programmer is not calling for hot water / switch is not set to constant
BurnerIf flashing this indicates a PCB fault
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