Slant/Fin
Slant/Fin Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Boiler will not fire; control display shows E01 lockout.
Ignition Failure Lockout
E02
Boiler shuts down and displays E02; burner stops shortly after ignition attempt.
Flame Loss During Run
E03
Boiler locks out with E03; no ignition, inducer may run briefly then stop.
Pressure Switch or Combustion Air Proving Fault
E04
Boiler display shows E04 and shuts down, often after running for a short period.
High Limit Temperature Lockout
E05
Boiler shows E05, will not start; fan or pump may run but burner does not light.
Low Water Cutoff or Water Level Fault
E06
Boiler display shows E06; boiler shuts down and may restart after cooling.
Flue Gas Overheat or Flue Temperature Sensor Fault
E07
Boiler shows E07, no heat; circulator may run without burner firing.
Outdoor Reset Sensor Fault or Open Sensor Circuit
E08
Boiler display shows E08; system will not fire, and may occur after a power surge.
Internal Control Board Fault
E09
Boiler shows E09; burner shuts down, and may coincide with high flue temperature or poor combustion.
Flame Signal Weak or Intermittent
E10
Boiler display shows E10, no heat, and the circulator may not run.
System Sensor or Supply Water Temperature Sensor Fault
E11
Boiler shows E11, the burner will not start, and this may occur after thermostat wiring changes.
Thermostat / Demand Input Fault
E12
Boiler display shows E12, indicating intermittent operation, which may coincide with power issues.
Line Voltage or Frequency Fault
E13
Boiler shows E13, the burner stops, and this may be associated with condensate issues on high-efficiency Slant/Fin boilers.
Condensate Overflow or Float Switch Trip
E14
Boiler display shows E14, the burner will not light, and the inducer may not start.
Inducer Motor or Combustion Fan Fault
E15
Boiler shows E15, indicating intermittent lockouts, which may coincide with multiple rapid restarts.
Excessive Lockouts / Retry Limit Exceeded
Symptom
Boiler display is blank or unreadable but boiler still runs
Display Module Failure
Symptom
Boiler frequently needs manual reset due to rollout or spill switch trips
Flue Gas Spillage / Rollout Condition
Symptom
Boiler frequently shuts down on flame failure during windy conditions
Wind-Induced Flame Loss / Venting Issue
Symptom
Boiler ignites with a loud boom or puff back
Delayed Ignition
Symptom
Boiler operates but emits a metallic or burning smell
Overheating Components / Electrical Overload
Symptom
Boiler pressure rises excessively when heating; the relief valve opens frequently.
Overpressure / Expansion Tank Failure
Symptom
Boiler vibrates or rattles loudly during operation
Mechanical Vibration / Loose Components
Symptom
Boiler will not start at all; there are no lights or display, and it is completely dead.
No Power to Boiler
Symptom
Radiators or baseboards on upper floors are cold while lower floors heat.
Air-Bound System / Poor Circulation to Upper Levels
Symptom
Strong fuel or gas smell near the boiler.
Gas Leak / Fuel Leak
Symptom
The boiler base or jacket shows rust and corrosion, with occasional dripping.
Boiler Section or Heat Exchanger Leak
Symptom
The boiler cycles on and off, but the thermostat never reaches the set temperature.
Insufficient Heat Output / Underfiring
Symptom
The boiler emits a rumbling or roaring noise during operation.
Combustion Noise / Improper Combustion
Symptom
The boiler frequently locks out on low water, even though the system appears full.
Nuisance Low Water Cutoff Trips
Symptom
The boiler makes loud banging or knocking noises when firing or shortly after.
Kettling / Boiling in Heat Exchanger
Symptom
The boiler room is unusually hot; the boiler seems to run constantly.
Boiler Overfiring / Control Failure
Symptom
The boiler runs, but domestic hot water is insufficient or fluctuates (on combi or indirect systems).
Domestic Hot Water Priority / Control or Flow Issue
Symptom
The boiler runs, but the house does not heat, and radiators or baseboards stay cool.
No Circulation / Circulator Pump Failure
Symptom
The boiler short cycles, turning on and off frequently without satisfying the thermostat.
Short Cycling / Improper Boiler Control
Symptom
Thermostat calls for heat but boiler does not start, zone circulator runs
Boiler Enable / Interlock Fault
Symptom
Water leaking from around the boiler or onto the floor.
System Leak / Relief Valve Discharge
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Boiler will not fire; control display shows E01 lockout.
|
Ignition Failure Lockout | View Details |
| E02 |
Boiler shuts down and displays E02; burner stops shortly after ignition attempt.
|
Flame Loss During Run | View Details |
| E03 |
Boiler locks out with E03; no ignition, inducer may run briefly then stop.
|
Pressure Switch or Combustion Air Proving Fault | View Details |
| E04 |
Boiler display shows E04 and shuts down, often after running for a short period.
|
High Limit Temperature Lockout | View Details |
| E05 |
Boiler shows E05, will not start; fan or pump may run but burner does not light.
|
Low Water Cutoff or Water Level Fault | View Details |
| E06 |
Boiler display shows E06; boiler shuts down and may restart after cooling.
|
Flue Gas Overheat or Flue Temperature Sensor Fault | View Details |
| E07 |
Boiler shows E07, no heat; circulator may run without burner firing.
|
Outdoor Reset Sensor Fault or Open Sensor Circuit | View Details |
| E08 |
Boiler display shows E08; system will not fire, and may occur after a power surge.
|
Internal Control Board Fault | View Details |
| E09 |
Boiler shows E09; burner shuts down, and may coincide with high flue temperature or poor combustion.
|
Flame Signal Weak or Intermittent | View Details |
| E10 |
Boiler display shows E10, no heat, and the circulator may not run.
|
System Sensor or Supply Water Temperature Sensor Fault | View Details |
| E11 |
Boiler shows E11, the burner will not start, and this may occur after thermostat wiring changes.
|
Thermostat / Demand Input Fault | View Details |
| E12 |
Boiler display shows E12, indicating intermittent operation, which may coincide with power issues.
|
Line Voltage or Frequency Fault | View Details |
| E13 |
Boiler shows E13, the burner stops, and this may be associated with condensate issues on high-efficiency Slant/Fin boilers.
|
Condensate Overflow or Float Switch Trip | View Details |
| E14 |
Boiler display shows E14, the burner will not light, and the inducer may not start.
|
Inducer Motor or Combustion Fan Fault | View Details |
| E15 |
Boiler shows E15, indicating intermittent lockouts, which may coincide with multiple rapid restarts.
|
Excessive Lockouts / Retry Limit Exceeded | View Details |
| – |
Boiler display is blank or unreadable but boiler still runs
|
Display Module Failure | View Details |
| – |
Boiler frequently needs manual reset due to rollout or spill switch trips
|
Flue Gas Spillage / Rollout Condition | View Details |
| – |
Boiler frequently shuts down on flame failure during windy conditions
|
Wind-Induced Flame Loss / Venting Issue | View Details |
| – |
Boiler ignites with a loud boom or puff back
|
Delayed Ignition | View Details |
| – |
Boiler operates but emits a metallic or burning smell
|
Overheating Components / Electrical Overload | View Details |
| – |
Boiler pressure rises excessively when heating; the relief valve opens frequently.
|
Overpressure / Expansion Tank Failure | View Details |
| – |
Boiler vibrates or rattles loudly during operation
|
Mechanical Vibration / Loose Components | View Details |
| – |
Boiler will not start at all; there are no lights or display, and it is completely dead.
|
No Power to Boiler | View Details |
| – |
Radiators or baseboards on upper floors are cold while lower floors heat.
|
Air-Bound System / Poor Circulation to Upper Levels | View Details |
| – |
Strong fuel or gas smell near the boiler.
|
Gas Leak / Fuel Leak | View Details |
| – |
The boiler base or jacket shows rust and corrosion, with occasional dripping.
|
Boiler Section or Heat Exchanger Leak | View Details |
| – |
The boiler cycles on and off, but the thermostat never reaches the set temperature.
|
Insufficient Heat Output / Underfiring | View Details |
| – |
The boiler emits a rumbling or roaring noise during operation.
|
Combustion Noise / Improper Combustion | View Details |
| – |
The boiler frequently locks out on low water, even though the system appears full.
|
Nuisance Low Water Cutoff Trips | View Details |
| – |
The boiler makes loud banging or knocking noises when firing or shortly after.
|
Kettling / Boiling in Heat Exchanger | View Details |
| – |
The boiler room is unusually hot; the boiler seems to run constantly.
|
Boiler Overfiring / Control Failure | View Details |
| – |
The boiler runs, but domestic hot water is insufficient or fluctuates (on combi or indirect systems).
|
Domestic Hot Water Priority / Control or Flow Issue | View Details |
| – |
The boiler runs, but the house does not heat, and radiators or baseboards stay cool.
|
No Circulation / Circulator Pump Failure | View Details |
| – |
The boiler short cycles, turning on and off frequently without satisfying the thermostat.
|
Short Cycling / Improper Boiler Control | View Details |
| – |
Thermostat calls for heat but boiler does not start, zone circulator runs
|
Boiler Enable / Interlock Fault | View Details |
| – |
Water leaking from around the boiler or onto the floor.
|
System Leak / Relief Valve Discharge | View Details |
No matching codes found
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