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Chapter 6. Maintenance and Inspection
  Alarm codes and details
When lockout occurs, an alarm code is displayed automatically. When an alarm 
occurs, the sequence number and alarm code issued when the lockout.”
If the sequence cannot be specified, the sequence code displayed when lockout 
occurred may be shown as [– –] (stopped).
Alarm 
code
Sub-
code
Description Status
Cancellation 
method
E 1
None False ame The ame signal is detected for 15 s during prepurge Reset
E6
Ignition failure Ignition was not detected during the lockout time.  Reset
E7
Flame failure The ame signal disappeared during standby for normal combustion or thereafter. Reset
E9 02
Switch input error The DISP switch, RESET switch or reset input stayed on for 60 seconds.
Or, one minute passed with the contact reset input ON.
Note: Monitoring is continuous while power is supplied.
Reset
E9 03
Internal relay feedback (K1) Relay K1 failure (contact welding)
Note:  If this error recurs even after a manual reset, a device failure may have 
occurred.
Reset
E9 05
Terminal 7 voltage discrepancy 
(PV)
At terminal 7, while pilot valve or main valve output was OFF, voltage was detected 
for 30 seconds. 
Note:  This error can occur because of a ground fault, voltage supply to terminal 
7 from an external circuit (bypass circuit, etc.), or relay K3 failure (contact 
welding, etc.).
Reset
E9 06
Terminal 8 voltage discrepancy 
(MV)
At terminal 8, while main valve output was OFF, voltage was detected for 30 
seconds.
Note:  This error can occur because of a ground fault, voltage supply to terminal 
8 from an external circuit (bypass circuit, etc.), or relay K4 failure (contact 
welding, etc.).
Reset
E9 07
Terminal 6 voltage discrepancy 
(IG)
At terminal 6, while the ignition transformer output was OFF, voltage was detected 
for 30 seconds.
Note:  This error can occur because of a ground fault, voltage supply to terminal 
6 from an external circuit (bypass circuit, etc.), or relay K5 failure (contact 
welding, etc.).
Reset
E9 08
Alarm generation when power 
is turned ON
When the cause of lockout cannot be identied
• Power was turned o before CPU error judgment after lockout occurred
• Latch relay was set to lockout due to vibration during transport or for other reasons
This does not indicate a problem with the device. Reset the device to restore normal 
operation.
Reset
E9 50
ROM failure ROM check code error Reset
E9 5
 
1
Memory read error Internal memory read error Reset
E9 52
Memory write error Internal memory write error Reset
E9 53
Memory data error Internal memory check code error Reset
E9 54
CPU communication error CPU communication error Reset
E9 55
Diagnosis of the input circuit Detection of part failure (voltage applied to the input terminal by wrong wiring) or 
strong inductive electrical noise to the signal wire
Reset
E9 56
Input safety pulse error Internal clock error Reset
E9 57
CPU diagnosis (EEPROM data 
error)
Error during CPU check
• Because of EEPROM failure, EEPROM data diered
Reset
E9 58
CPU diagnosis (parameters) Error during CPU check Reset
E9 59
CPU diagnosis (timer) Error during CPU check Reset
E9 60
CPU diagnosis (process) Error during CPU check Reset
E9 6
 
1
CPU diagnosis (process 
synchronization)
Error during CPU check Reset
E9 62
Alarm relay timeout Internal feedback signal error of alarm output relay Reset
E9 63
CPU diagnosis Internal memory data error Reset
E9 64
Flame circuit diagnosis Error in the circuit for diagnosing the ame detector circuit Reset
E9 65
Flame circuit diagnosis Error in the interactive diagnosis of the ame detector circuit Reset
E9 66
K1 relay circuit error Internal fuse blown, or internal feedback signal error Reset
E9 68
K3 relay circuit error (PV) Internal feedback signal error Reset
E9 69
K4 relay circuit error (MV) Internal feedback signal error Reset
E9 70
K5 relay circuit error (IG) Internal feedback signal error Reset
E9 7
 
1
POC (shuto valve proof of 
closure) setting error or internal 
memory read error
Internal memory read error
• Because of EEPROM failure, EEPROM data diered
Reset
Note: If lockout occurs even if reset is repeated, the device has failed.