MHG Heating Ltd ©
MHG Heating Ltd Unit 4 Epsom Downs Metro Centre Waterfield Tadworth Surrey KT20 5LR
Phone: 0845 6448802 Fax: 0845 6448803 Email:
010911
Enhanced Fault Diagnosis Codes (LMU Internal Software Diagnostic Codes)
If required a more detailed fault diagnosis code can be viewed. This will assist where a definitive
cause for a repeated operational error cannot be found.
The enhanced fault diagnosis code is displayed at b0 within the second INFO level.
Access to this level can is detailed on page three of this guide.
The table below indicates a limited number of enhanced fault codes. If the exact number indicated
by the appliance is not detailed below please call our Technical Department or guidance.
Fault Code
Fault Description
83
Combustion Fan Not Reaching Ignition Speed
87
Combustion Fan Operating Beneath Minimum Setting
90
Combustion Fan Not Reaching Pre Purge Speed
96
Flame Rectification Signal Detected When Burner Off
97
Flame Rectification Signal Detected When Burner Off
98
Flame Signal Lost During Operation
99
Flame Signal Lost During Operation
100
Flame Signal Lost During Operation
101
Flame Signal Not Detected Following Last Ignition Attempt
102
Flame Signal Not Detected Following Last Ignition Attempt
170
The Reset Button is being Continually Depressed. (Possible Display Module Mounting Error.)
259
The Reset Button Has Been Pressed When No Error Has Been Displayed (E153 Generator.)
282
Combustion Fan Not Reaching Correct Speed
400
System Hydraulic Error. Return Temperature > Flow Temperature. (Repeatedly.)
401
System Hydraulic Error. Return Temperature > Flow Temperature. (Repeatedly.)
402
System Hydraulic Error. Return Temperature > Flow Temperature. (Repeatedly.)
403
System Hydraulic Error. Return Temperature > Flow Temperature. (Repeatedly.)
404
System Hydraulic Error. Return Temperature > Flow Temperature. (Repeatedly.)
406
Boiler Flow Temperature Rising to Above Maximum Limit Temperature When Burner Is On.
422
Boiler Flow Temperature Rising to Above Maximum Limit Temperature When Burner Is Off.
433
System Hydraulic Error.
Δ
T between Flow and Return Too High. (Repeatedly.)
434
System Hydraulic Error.
Δ
T between Flow and Return Too High. (Repeatedly.)
435
System Hydraulic Error.
Δ
T between Flow and Return Too High. (Repeatedly.)
