This is the full list of diagnostics- (It is useful for at least ruling out some other possible faults too)

000 Normal Operation
010 Overvoltage Check voltage between terminals 1(red) and 2(brown) at connector.
(B1). This must be less than 16 volts.
Check battery, electrical leads and vehicle charging system.
011 Under voltage shut down Check voltage between terminals 1(red) and 2(brown) at
connector (B1). This must be greater than 10.2 volts
Check battery, electrical leads and vehicle charging system.
012 Overheating Check for possible causes of overheat (water circuit), Sensor.
Check overheat switch resistance values. Temperature at
temperature sensor or overheat sensor is greater than 125°C.
014 Possible overheating detected Difference of measured values at temperature sensor >15°C
(difference evaluation) (min. 70°C water temperature and metering pump in operation);
Check temperature sensor and overheating sensor,
replace if necessary. Check values from previous page.
015 Too many overheats Remove cause of over heat. Reset control unit using 7 day
timer or fault code retrieval device to unlock control unit. Permanent
overheating counter reading exceeded. Heating enable only
possible by means of diagnostics system (press both “LL” keys
simultaneously).
017 Overheating detected Temperature at temperature or overheating sensor > 130 °C,
emergency OFF if Fault Code 012 or 014 not applicable; check water
circuit, check temperature sensor and overheating sensor; replace if
necessary. See graph on previous page.
020 Open circuit - glow pin Check glow pin and electrical leads for continuity, replace if
necessary.
021 Short circuit - glow pin Check glow pin and electrical leads for continuity, replace if
necessary.
030 Combustion air blower motor Blower impeller or electric motor may be jammed (frozen solid, dirty,
etc.) Fix jam, replace electric motor if necessary.
031 Combustion air blower motor Check lead to combustion air motor for continuity, replace
motor if necessary.
032 Combustion air blower motor short-circuit Check combustion air blower motor (electric motor); replace if
necessary. Check power supply (chafed, corroded etc.)
038 Vehicle fan relay control break Check electric lead to relay, fix break, replace relay if necessary
For wiring harness (P/N CA1 60 401) without relay, replace harness.
039 Vehicle fan relay control short circuit Check electric lead to relay, fix break, replace relay if necessary
For wiring harness (P/N CA1 60 401) without relay, replace harness.
041 Water pump break Check supply lead to water pump for continuity, remedy break,
replace water pump if necessary.
042 Water pump short-circuit Check supply lead to water pump for short circuit, check water
pump, replace water pump if necessary.
26
Maintenance / Troubleshooting / Repair
Fault Code Fault Description Causes / Repair
27
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 to metering pump for continuity, remedy break,
replace if necessary.
050 Too many 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 high mode Heater has started successfully the flame has extinguished.
Check fuel supply. Check combustion air and exhaust flow.
056 Flame cutout in low mode 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 > 2 M ? (if open circuit).
061 Short circuit - external temperature sensor Check connections. Check sensor resistance values between
11 and 12 at connector B2 < 50 ? (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 13 and 14 at connector
B2 > 3040 ? (if open circuit).
065 Short circuit - flame sensor Check connection leads. Resistance values between 13 and 14 at
connector B2 > 780 ? (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 > 2 M ? (if open circuit).
072 Short circuit - overheat sensor Check connection leads. Resistance values between 9 and 10 at
connector B2 < 50 M ? (if short circuit).
090 Control unit defect (internal fault) Control unit malfunction due to interference voltage from
092 Control unit defective(ROM error) vehicle electrical system; possible causes low batteries, charges,
093 Control unit defective(RAM error) other sources of interference, eliminate interference voltages.
Internal faults detected in microprocessor/ memory detected.
Replace control unit.
097 Control unit defective (power failure) Internal failure. Replace control unit. 
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