| Fault code number and meaning | Possible cause of fault | Fault rectification with remarks |
| 000 | | |
| No malfunction | | |
| 001 | | |
| Overvoltage warning (> 16 V) | Controller | Renew |
| 002 | | |
| Undervoltage warning (< 10.2 V) | 2nd. battery | Charge |
| 010 | | |
| Overvoltage shut-off (> 16 V) | 2nd. battery | Voltage was present for longer than 20 seconds |
| 011 | | |
| Undervoltage shut-off (< 10.2 V) | 2nd. battery | Voltages were present for longer than 20 seconds |
| 012 | | |
| Overheating | Temperature at flame monitor -G64- or overheating sensor -G189- too high (> 125 °C). | Air in coolant circuit, bleed → Chapter |
| 014 | | |
| Evaluation of temperature difference between flame monitor -G64- and overheating sensor -G189- | Air in coolant circuit, flame monitor -G64- defective, overheating sensor -G189- defective | Bleed → Chapter, check flame monitor -G64- → Chapter, check overheating sensor -G189- → Chapter |
| 015 | | |
| Continuous shut-down | Air in coolant circuit, | Bleed → Chapter Clear fault memory → Chapter |
| 017 | | |
| Overheating | Temperature too high (> 130 °C) at overheating sensor -G189- and coolant temperature sender for heater -G241- | Air in coolant circuit, bleed → Chapter Check overheating sensor -G189- → Chapter Check coolant temperature sender for heater -G241- → Chapter Clear fault memory → Chapter |
| 020 | | |
| Glow plug for heater -Q9- | Defective | Renew |
| 021 | | |
| Short circuit on the glow plug for heater -Q9- | Short circuit on the connection or in the glow plug | Renew if necessary. |
| 030 | | |
| Combustion air blower -V6- | Blocked | Renew |
| 032 | | |
| Combustion air blower -V6- | Open circuit | Check the connection, replace if necessary |
| 038 | | |
| Fresh air blower -V2- | Open circuit | Check, |
| 039 | | Renew if necessary. |
| Fresh air blower -V2- | Short circuit | |
| 041 | | |
| Circulation pump -V55- | Open circuit | Check, replace if necessary |
| 042 | | and bleed coolant circuit → Chapter |
| Circulation pump -V55- | Short circuit | |
| 047 | | |
| Metering pump -V54- | Short circuit | Check, |
| 048 | | Renew if necessary. |
| Metering pump -V54- | Open circuit | |
| 050 | | |
| Continuous shut-down | Unsuccessful start attempts | Erase fault memory → Chapter. |
| 051 | | |
| Time overrun | When blowing flame monitor -G64- cold with combustion air blower -V6- | Check flame monitor -G64- → Chapter. |
| 052 | | |
| Time overrun | Safety time exceeded after several start attempts | Check: exhaust pipe fuel volume, combustion air induction |
| 053 | | |
| Flame failure from the high control level | Metering pump -V54- (quantity delivered) Exhaust pipe (blocked) Combustion air (insufficient) | Check, |
| 054 | Flame monitor -G64- (values) | Replace if necessary → Chapter |
| Flame failure from medium control level | The fault memory is cleared if the start is successful. | |
| 056 | Heater is permanently switched off. | |
| Flame failure from low control level | Clear fault memory after checking and replacing. | Switch on heater once again. |
| 060 | | |
| Coolant temperature sender for heater -G241- | Open circuit | Check water temperature, |
| 061 | | Check coolant temperature sender for heater -G241-, |
| Coolant temperature sender for heater -G241- | Short circuit | Replace if necessary → Chapter |
| 064 | | |
| Flame monitor -G64- | Open circuit | Flame monitor -G64- |
| 065 | | Checking → Chapter |
| Flame monitor -G64- | Short circuit | |
| 071 | | |
| Overheating sensor -G189- | Open circuit | Check, |
| 072 | | |
| Overheating sensor -G189- | Short circuit | Replace if necessary → Chapter |
| 090 | | |
| Heater control unit -J162- | Error in microprocessor, (memory present) | Replace if necessary → Chapter |
| 091 | | |
| Interference voltage | In vehicle electrical system or other voltage sources | Rectify |
| 092 to 103 | | |
| Heater control unit -J162- | Defective | Replacing → Chapter. |
