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WEBASTO THERMO 300 6BASIC TROUBLESHOOTING
6-3
Failure Symptom
1X Flash (F 01)
No combustion after
completion of start up
sequence
2X Flashes (F 02)
Flame out during
burner operation and
no restart possible
3X Flashes (F 03)
Low voltage for more
than 20 seconds
4X Flashes (F 04)
Flame detector
recognizes false flame
signal during pre-start
or shut-down cycle
5X Flashes (F 05)
Flame detector
6X Flashes (F 06)
Temperature sensor
7X Flashes (F 07)
Fuel solenoid valve
8X Flashes (F 08)
Combustion air fan
motor
9X Flashes (F 09)
Circulation pump
motor
10X Flashes (F 10)
Temperature limiter
11X Flashes (F 11)
Electronic ignition coil
12X Flashes (F 12)
Heater lock-out
Probable Cause
-Fuel system
- Combustion air
- Electronic ignition
- Fuel supply (shortage of fuel)
- Electrical system
- Defective flame detector
- Wiring
- Defective flame detector
- Wiring
- Defective temperature sensor
- Wiring
- Defective solenoid valve
- Wiring
- Wrong RPM
- Defective combustion air fan motor
- Wiring
- Defective circulation pump motor
- Overheat condition
- Coolant flow
- Wiring
- Defective temperature limiter
- Wiring
- Defective electronic ignition coil
3 repeated faults/flame-outs or
5 repeated start attempts
Check and Correct
- Fuel level
- Type of fuel being used
- Fuel filter
- Fuel line connections (air bubbles in fuel lines)
- Fuel nozzle plugged
- Air intake or exhaust, restricted or plugged
- Incorrect electrode gap
- Restriction in the fuel system
- Fuel filter
- Fuel line connections (air bubbles in fuel lines)
- Type of fuel being used (waxing)
- Load test batteries
- Corrosion at connections
- Loose connections
- Replace flame detector
- Damaged wiring, open or short circuit
- Replace flame detector
- Damaged wiring, open or short circuit
- Replace temperature sensor
- Damaged or corroded wiring
- Open or short circuit
- Replace solenoid valve
- Damaged wiring, open or short circuit
- Replace combustion air fan
- Replace combustion air fan
- Damaged wiring, open or short circuit
- Replace circulation pump motor
- Reset temperature limiter
- Coolant level or flow restriction
- Air trapped in coolant circuit
- Damaged or corroded wiring
- Open or short circuit
- Replace temperature limiter
- Damaged wiring, open or short circuit
- Replace electronic ignition coil
Re-initialize control unit by switching heater on,
disconnecting and connecting power connection.
6.3 Operational Malfunction Symptoms via Flash/ Malfunction Code
The following table lists the possible malfunctions which can be read by flashing code or read directly off of an
appropriate timer or with the PC diagnostics kit.
Table 6-1: Operational Failure Symptoms (Control Unit SG 1572 D)