27
Maintenance / Troubleshooting / Repair
Fault Code Fault Description
Causes / Repair
047
Short circuit - fuel metering pump
Check for wires for short to fuel metering pump. Test fuel metering
pump.Replace if necessary.
048
Open circuit - fuel metering pump
Check supply lead tometering pump for continuity, remedy break,
replace if necessary.
050
Toomany no start attempts
Safety time counter reading exceeded.Reset control unit using 7
day timer or fault code retrieval device to unlock control unit.
051
Faulty flame recognition
At start, if flame sensor is a above 70°C > 240 seconds; check
exhaust gas and combustion air supply, check flame sensor, replace
if necessary. For flame sensor values see graph on previous page.
052
No start safety time exceeded
No flame detected on start attempt.Check fuel delivery and fuel
supply, Check exhaust gas and combustion air ducts.
053
Flame cutout in boost mode
Heater has started successfully the flame has extinguished.
Check fuel supply.Check combustion air and exhaust flow. Check
flame sensor resistance value.Replace flame sensor if necessary.
054
Flame cutout in highmode
Heater has started successfully the flame has extinguished.
Check fuel supply. Check combustion air and exhaust flow.
056
Flame cutout in lowmode
Check flame sensor resistance value.
060
Open circuit - temperature sensor
Temperature sensor detects a value beyond it's range.
Check connections.Check sensor resistance values between
11 and 12 at connector B2 > 2M
Ω
(if open circuit).
061
Short circuit - external temperature sensor
Check connections.Check sensor resistance values between
11 and 12 at connector B2 < 50
Ω
(if short circuit).
Temperature sensor values on previous pages.
064
Open circuit - flame sensor
Sensor is sensing value outside of range.Check connection leads.
Resistance values between 1 and 2 at connector
B2 > 3040
Ω
(if open circuit).
065
Short circuit - flame sensor
Check connection leads. Resistance values between 1 and 2 at
connector B2 > 780
Ω
(if short circuit). Flame sensor values on
page 17.
071
Open circuit - overheat sensor
Check connection leads.Resistance values between 9 and 10 at
connector B2 > 2M
Ω
(if open circuit).
072
Short circuit - overheat sensor
Check connection leads.Resistance values between 9 and 10 at
connector B2 < 50M
Ω
(if short circuit).
091
External interference voltage
Error in controller from interference voltage from vehicle network pos-
sible causes: poor batteries, poor battery charges, other interference
sources; eliminate interference voltages.
090
Controller defect
Control unit malfunction due to interference voltage from vehicle elec-
092 -103
trical system; possible causes low batteries, charges, other sources
of interference, eliminate interference voltages.
Internal faults detected in
microprocessor/ memory.Replace control unit.
Internal failure. Replace control unit.
Faults not shownby the diagnosis system
After switching
HYDRONIC
on, thewater pump and vehicle fan start
HYDRONIC
won’t start
immediately.
· Remove and check temperature sensor.
After switching
HYDRONIC
on, the vehicle fan starts, functioning
“pre-venting” is activated.
· Changeover venting toheatingat “heating/ventingchangeover switch.
