Webasto DUAL TOP RHA-100 Workshop Manual - page 14
3 Fault code output
Dual Top
306
Message 17
Failure control unit
Control unit (heater) fault / heater
locked
1 Put heater back into service (see above this table) and
restart heater.
2 Replace control unit.
Message 18
Failure cabin temperature
sensor
Interior temperature sensor
disconnection / short circuit
1 Check routing of cable, ensure that it is not pinched or
crushed,
check the connector behind the control panel.
Reset heater (by pressing OK or switching off for at
least 5 sec.)
2 Replace interior temperature sensor.
Message 19
n/a
n/a
Message 20
Failure heating air
temperature sensor
Hot air temperature sensor
disconnection
1 Check routing of cable, ensure that it is not pinched or
crushed, check the connectors.
2 Check resistance of hot air temperature sensor.
3 Reset heater (by pressing OK or switching off for at
least 5 sec.)
4 Replace sensor wiring harness.
Message 21
Failure heating air
temperature sensor
Hot air temperature sensor short
circuit
See message 20.
Message 22
Failure sanitary water
temperature sensor
Water temperature sensor
disconnection
1 Check routing of cable, ensure that it is not pinched or
crushed, check the connectors.
2 Check resistance of water temperature sensor.
3 Reset heater (by pressing OK or switching off for at
least 5 sec.)
4 Replace sensor wiring harness.
Message 23
Failure sanitary water
temperature sensor
Water temperature sensor short
circuit
See message 22.
Message 24
Failure glow plug
Glow plug / flame detector
disconnection
1 Check routing of cable, ensure that it is not pinched or
crushed, check the connectors.
2 Check resistance of glowplug.
3 Reset heater (by pressing OK or switching off for at
least 5 sec.)
4 Replace burner (incl. glowplug and evaporator
housing assy).
Message 25
Failure glow plug
Glow plug / flame detector short
circuit
See message 24.
Message 26
Failure flame detection
Early flame detection
See message 24.
Message 27
Failure relay box
Short circuit of 230V indication
signal from relay box to heater
1 Check wiring harness relaybox to heater.
2 Check the relay box and wiring connections.
3 Check Control Panel and connections Control Panel.
4 Check internal wiring harness connections Y9, Y10.
Message 28
Failure drain valve
Electrical drainage valve
disconnection
1 Check routing of cable, ensure that it is not pinched or
crushed, check the connectors.
2 Check function of valve with separate 12V DC power
supply.
3 Reset heater (by pressing OK or switching off for at
least 5 sec.)
4 Replace solenoid valve.
Message 29
Failure drain valve
Electrical drainage valve short circuit See message 28.
Message 30
Failure relay
230V high or low power relay circuit
interrupted / short circuit
See message 27.
Message 31, 32, 33
n/a
n/a
Table 302: Fault messages programmable Control Panel
Message
Meaning
Remedy