Webasto Thermo 90 ST Operating Instructions Manual - Cause Remedy
If a fault occurs, check that the fuses and plug connections are in perfect condition and se-
cure.
If this action does not correct the defect, consult your authorised Webasto dealer.
After the heater has been shut down due to a fault lock-out, a coded flashing signal is emit-
ted through the operation indicator during the run-on time of the heater. These coded flash-
ing signals are designed to assist the authorised Webasto dealer in diagnosing the fault.
When equipped with the standard timer, a fault output appears in the display after a fault
occurs.
Cause Remedy
No combustion after
starting and restarting.
Flame goes out during
operation.
Switch off heater and switch on again.
If the heater fails to re-start consult your
authorised Webasto dealer.
Voltage drop for more
than 20 seconds.
Check fuses, electrical connections and
battery.
Heater has overheated due to
lack/loss of coolant.
Top up coolant in accordance with the
vehicle manufacturer's instructions.
Action in the event of faults
Heater switches off automatically (= fault lock-out)