Incorrect Function - Chaffoteaux & Maury Britony Combi SE Maintenance And Service Manual

Incorrects functions is signalled by leds (rep 22) display flashing correspond with chart below.
CODE
30 40 50 60 70
H H H H H
H H H H G
H H H H G
H H H G H
H H H G H
H H H G G
H H G H H
H H G H G
H H G H G
H H G G H
H G H H H
H G H G H
H G H G G

INCORRECT FUNCTION

FAULT
80
G
Overheat sensor switch open.
H
Overheating defect without lock out.
G
No flame detection.
H
Ionisation printed circuit board faulty.
G
Anti-frost mode on (pump in operation).
H
Anti-frost mode on (burner and pump in operation).
G
Domestic hot water thermistor faulty (open circuit).
H
Domestic hot water thermistor faulty (short circuit).
G
Central heating thermistor flow faulty (open circuit).
H
Central heating thermistor flow faulty (short circuit).
G
Low water pressure in the Central Heating circuit.
G
Fan on but does not activate air pressure switch.
H
Fan off but air pressure switch fails to return to off position.
10