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Every SDMO engine fault code in our verified reference — 118 codes, 14 of them with a documented remedy. Find your code in the table, read the likely causes, then work the remedy. If it is beyond a field fix, our workshop in Embakasi repairs SDMO controllers and engines at board level.
Covers: APM303 · APM403 · MICS Telys · Model · TELYS1
| Code | Fault | Likely cause | Remedy |
|---|---|---|---|
| 1-Jun | Overload or short-circuit fault | The alternator has detected an overload or short-circuit | — |
| 13-0 | Maximum alternator voltage alarm | The alternator output voltage exceeds the warning threshold. | — |
| 13-0 | Exhaust temperature sensor failure | The exhaust temperature sensor is malfunctioning | — |
| 13-1 | Maximum alternator voltage fault | The alternator output voltage is critically high | — |
| 14-0 | Minimum alternator frequency alarm | The alternator output frequency is below the warning threshold (e.g. | — |
| 14-0 | Fuel pump relay failure | The fuel pump relay is malfunctioning | — |
| 14-1 | Minimum alternator frequency fault | The alternator output frequency is critically low | — |
| 15-0 | Maximum alternator frequency alarm | The alternator output frequency exceeds the warning threshold (e.g. | — |
| 15-0 | Starter relay failure | The starter relay is malfunctioning | — |
| 15-1 | Maximum alternator frequency fault | The alternator output frequency is critically high | — |
| 16-0 | Control panel power supply failure | The control panel power supply is outside acceptable limits. | — |
| 16-1 | Option 3 module CAN bus fault | The CAN bus communication with the optional module 3 has failed. | — |
| 17-0 | Engine oil filter restriction alarm | The oil filter is clogged | — |
| 17-1 | Option 4 module CAN bus fault | The CAN bus communication with the optional module 4 has failed. | — |
| 18-0 | Alternator frequency sensor failure | The alternator frequency sensor is malfunctioning | — |
| 18-1 | Option 5 module CAN bus fault | The CAN bus communication with the optional module 5 has failed. | — |
| 19-1 | Option 6 module CAN bus fault | The CAN bus communication with the optional module 6 has failed. | — |
| 20-0 | Alternator phase imbalance alarm | The alternator output shows an imbalance between phases | — |
| 20-1 | Alternator phase imbalance fault | The alternator output phase imbalance is critical | — |
| 21-1 | Spare RS485 communication fault | The RS485 communication link for a spare module has failed. | — |
| 22-1 | Hardware watchdog fault | The control panel’s internal watchdog timer has detected a hardware or software malfunction. | — |
| 23-0 | Fuel pump failure alarm | The fuel pump is not operating correctly | — |
| 23-1 | Fuel pump failure fault | The fuel pump has failed critically | — |
| 24-0 | Air intake restriction alarm | The air intake system is restricted | — |
| 24-1 | Air intake restriction fault | The air intake restriction is critical | — |
| 25-0 | Normal contactor open alarm (system side) | The normal power contactor (system side) is open when it should be closed. | — |
| 26-0 | Emergency contactor open alarm (generating set side) | The emergency power contactor (generator side) is open when it should be closed. | — |
| 27 | Minimum alternator voltage reached or dipped below the set threshold | triggering a shutdown. | — |
| 27-1 | Oil temperature fault | The engine oil temperature has exceeded the safe operating limit | — |
| 28-1 | Oil level low fault | The engine oil level is critically low | — |
| 29-0 | No water preheating alarm | The water preheating system is not functioning | — |
| 29-1 | No water preheating fault | The water preheating system failure is critical | — |
| 30-0 | Differential trigger alarm | The differential protection system has detected an imbalance in current | — |
| 30-1 | Differential trigger fault | The differential protection system has detected a severe current imbalance | — |
| 31-0 | Permanent insulation monitor trigger alarm | The insulation monitoring system has detected a warning-level insulation fault in the electrical system. | — |
| 31-1 | Permanent insulation monitor trigger fault | The insulation monitoring system has detected a critical insulation fault | — |
| 32-1 | Differential relay connection fault | The differential protection relay has a connection or operational failure. | — |
| 33-1 | Permanent insulation monitor connection fault | The insulation monitoring system has a connection or operational failure. | — |
| 34-0 | Battery charger fault alarm | The battery charger is not functioning correctly | — |
| 34-1 | Battery charger fault fault | The battery charger has a critical failure | — |
| 35-1 | Air cooler trip fault | The air cooler system has tripped | — |
| 36-1 | Air cooler low level fault | The coolant level in the air cooler system is critically low | — |
| 37-0 | Exhaust temperature high alarm | The exhaust temperature exceeds the warning threshold. | — |
| 37-1 | Exhaust temperature high fault | The exhaust temperature is critically high | — |
| 38-0 | Engine crank failure alarm | The engine failed to crank properly during a start attempt | — |
| 38-1 | Engine crank failure fault | The engine failed to crank after multiple attempts | — |
| 39-0 | Generator overload warning | The generator is approaching its maximum load capacity | — |
| 39-1 | Generator overload fault | The generator has exceeded its maximum load capacity | — |
| 40-0 | Control panel temperature high alarm | The control panel temperature exceeds the warning threshold. | — |
| 40-1 | Control panel temperature high fault | The control panel temperature is critically high | — |
| 41-0 | Engine preheating relay failure | The engine preheating relay (e.g. | — |
| 41-1 | Engine preheating system fault | The engine preheating system has a critical failure | — |
| 42-0 | Fuel solenoid valve failure alarm | The fuel solenoid valve is not operating correctly | — |
| 42-1 | Fuel solenoid valve critical fault | The fuel solenoid valve has a critical failure | — |
| 43-0 | Alternator excitation failure alarm | The alternator excitation circuit is not functioning | — |
| 43-1 | Alternator excitation critical fault | The alternator excitation circuit has a critical failure | — |
| 44-0 | Engine shutdown solenoid failure alarm | The engine shutdown solenoid is not functioning | — |
| 44-1 | Engine shutdown solenoid critical fault | The engine shutdown solenoid has a critical failure | — |
| 45-0 | Control panel communication loss alarm | The control panel has lost communication with an external device (e.g. | — |
| 45-1 | Control panel communication critical fault | The control panel has a critical communication failure with an external device | — |
| 50/51 | Alternator short-circuit detected as current consumed reaches or exceeds the set threshold | triggering a shutdown. | — |
| 59 | Maximum alternator voltage reached or exceeded the set threshold | triggering a shutdown. | — |
| 81 | Minimum alternator frequency reached or dipped below the set threshold | triggering a warning or shutdown. | — |
| 81H | Maximum alternator frequency reached or exceeded the set threshold | triggering a warning or shutdown. | — |
| Alternator bearing temperature high | The alternator bearing temperature exceeds the safe limit | indicating potential bearing wear. | — |
| Alternator Overcurrent | The alternator output current exceeds the safe threshold | triggering a warning or shutdown. | — |
| Alternator phase sequence error | The alternator phase sequence is incorrect | causing electrical output issues. | — |
| Alternator temperature high | The alternator temperature exceeds the safe limit | triggering a warning or shutdown. | — |
| Aug-00 | Fuel level sensor failure | The fuel level sensor is malfunctioning | — |
| Battery Voltage Warning | Warning related to battery voltage levels being outside acceptable limits. | charge the battery; if above 14.8V | Measure battery voltage with a multimeter. If below 12.4V; check for overcharging. Inspect battery terminals and cables for corrosion or looseness; clean or tighten. Test the charging alternator or external charger for proper operation. Reset the fault by pressing the reset button after addressing the issue. to the APM403 or a technician if unresolved. |
| Camshaft position sensor failure | The camshaft position sensor is malfunctioning | affecting engine timing. | — |
| CAN bus communication failure | The CAN bus communication with the engine control unit or modules has failed. | opens; or loose connections. Verify all connected modules are powered and configured correctly. Reset the control panel and test communication. If the fault persists; consult the APM303 or a technician. | Inspect CAN bus wiring and connectors for shorts |
| Circuit breaker position inconsistent | Inconsistency between the motorised command from the circuit breaker and the position of the circuit breaker. | — | Inspect the circuit breaker for mechanical faults or sticking. Check the motorised control wiring and signals for faults. Verify the breaker’s position feedback mechanism. Reset the fault and test breaker operation. Consult the APM303 or a technician if unresolved. |
| Control module internal fault | The control module has detected an internal hardware or software error. | Power cycle the generator by disconnecting the battery for 30 seconds and reconnecting. Check for control module firmware updates in the SDMO APM303 . Inspect module wiring for faults. If the fault persists | replace the control module. Reset the fault and restart. Consult the APM303 or a technician if unresolved. |
| Crankshaft position sensor failure | The crankshaft position sensor is malfunctioning | affecting engine timing. | — |
| Dec-00 | Coolant level sensor failure | The coolant level sensor is malfunctioning | — |
| ECU Communication Failure | The engine control unit has lost communication with the control panel. | opens; or loose connections. Verify the ECU is powered and operational. Reset the control panel and test communication. If the fault persists; consult the APM403 or a technician. | Inspect CAN bus or other communication wiring between the ECU and control panel for shorts |
| Emergency stop | Emergency stop activated by pressing the emergency stop button | halting the generator. | — |
| Engine air intake temperature high | The air intake temperature exceeds the safe limit | affecting engine performance. | — |
| Engine Misfire | The engine control unit detects a misfire | indicating combustion irregularities. | — |
| Error Code | Meaning | Solution | — |
| Fault input no. x (x = 1 | 2 or 3) | Input configured in fault x is active | — |
| Flat battery | APM303 cannot start up the generating set due to critically low battery voltage. | Immediately charge the battery or replace it if it cannot hold a charge (below 11.5V for 12V systems). Inspect battery cables for damage or loose connections | repair as needed. Test the charging alternator; replace if faulty. Reset the fault and attempt to start. Consult the APM303 or a technician if unresolved. |
| Fuel pressure low | The fuel system pressure is below the required threshold | affecting engine performance. | — |
| Generating set shutdown failure | Generating set fails to shutdown properly after a shutdown request. | stuck solenoid; open circuit). Verify no external signals are preventing shutdown (e.g.; ATS). Reset the fault and test shutdown. Consult the APM303 or a technician if unresolved. | Check the control panel for proper shutdown signal transmission. Inspect the stop solenoid and wiring for faults (e.g. |
| Generating set start-up failure | Generating set fails to start up after a full starting sequence. | prime the system if needed. Verify battery voltage (above 12.4V for 12V systems); charge or replace if low. Inspect the starter motor and solenoid for faults | Check the fuel level and supply; check wiring. Test the fuel system for air or blockages. Reset the fault and attempt to start. to the APM303 or a technician if unresolved. |
| Governor failure | The engine governor is malfunctioning | affecting speed control. | — |
| High Alternator Frequency | The alternator output frequency exceeds the safe threshold | indicating an engine speed issue. | — |
| High coolant temperature | Engine coolant temperature is too high | triggering a shutdown. | — |
| High fuel temperature | The fuel temperature exceeds the safe operating limit | affecting engine performance. | — |
| High oil temperature | The engine oil temperature exceeds the safe operating limit | triggering a warning or shutdown. | — |
| Jul-00 | Engine temperature sensor failure | The engine temperature sensor has failed | — |
| KO ECU Air Intake Restriction | The engine control unit detects a restricted air intake | reducing engine performance. | — |
| KO ECU Alternator Temperature High | High alternator temperature detected by the engine control unit | indicating overheating. | — |
| KO ECU Battery Voltage High | High battery voltage detected by the engine control unit | indicating overcharging. | — |
| KO ECU Coolant Temperature HT | High temperature warning for engine coolant detected by the engine control unit. | radiator; hoses). Ensure proper airflow around the radiator. Test the coolant temperature sensor and wiring | Check the coolant level; top up with recommended coolant if low. Inspect the cooling system for leaks or blockages (e.g.; replace if faulty. Verify thermostat operation. Press the reset button after addressing the issue. Consult the APM403 or a technician if unresolved. |
| KO ECU Fuel Pressure Low | Low fuel pressure detected by the engine control unit | affecting performance. | — |
| KO ECU Fuel Pressure Sensor Failure | The fuel pressure sensor is malfunctioning | affecting fuel system monitoring. | — |
| KO ECU Fuel Temperature High | High fuel temperature detected by the engine control unit | affecting performance. | — |
| KO ECU Oil Pressure Low | Low oil pressure detected by the engine control unit | triggering a warning or shutdown. | — |
| KO ECU Oil Temperature Sensor Failure | The oil temperature sensor is malfunctioning | providing incorrect readings. | — |
| KO ECU Overspeed | The engine control unit detects an overspeed condition | exceeding safe limits. | — |
| KO ECU Phase Imbalance | The engine control unit detects an imbalance in alternator phase output. | redistribute loads to balance them. Inspect alternator output cables for loose or damaged connections. Test phase voltages with a multimeter to confirm balance. Check alternator windings for faults. Press the reset button on the APM403 panel after addressing the issue. to the APM403 or a technician if unresolved. | Check load distribution across all phases |
| KO ECU Shutdown Failure | The engine control unit detects a failure to shut down the engine properly. | stuck solenoid; open circuit). Verify no external signals (e.g.; ATS) are preventing shutdown. Test the control signal from the ECU. Press the reset button on the APM403 panel after addressing the issue. to the APM403 or a technician if unresolved. | Inspect the shutdown solenoid and wiring for faults (e.g. |
| KO ECU Starter Failure | The engine control unit detects a starter motor failure during a start attempt. | charge or replace if low. Test the starter motor and solenoid for operation; opens; or loose connections. Press the reset button on the APM403 panel after addressing the issue. to the APM403 or a technician if unresolved. | Check the battery voltage (above 12.4V for 12V systems); replace if defective. Inspect starter wiring for shorts |
| Low Alternator Frequency | The alternator output frequency is below the safe threshold | indicating low engine speed. | — |
| Low battery voltage or charging alternator malfunction | Battery voltage is below the set threshold or charging alternator malfunction | triggering a warning or shutdown. | — |
| Low coolant level | The engine coolant level is below the safe threshold | triggering a warning or shutdown. | — |
| Low Coolant Pressure | The engine coolant pressure is below the safe threshold | indicating a potential issue. | — |
| Low fuel level | Low fuel level detected in the daily service tank | triggering a warning or shutdown. | — |
| Low oil level | The engine oil level is below the safe threshold | triggering a warning or shutdown. | — |
| Low oil pressure | Engine oil pressure is too low or binary input is active | triggering a shutdown. | — |
| Nov-00 | Engine speed sensor failure | The engine speed sensor is malfunctioning | — |
| Oct-00 | Alternator voltage sensor failure | The alternator voltage sensor is malfunctioning | — |
| Overspeed | Generating set exceeds 120% of nominal speed | triggering a shutdown. | — |
| Sep-00 | Oil pressure sensor failure | The oil pressure sensor is malfunctioning | — |
| Starter motor failure | The starter motor failed to engage properly during a start attempt. | charge or replace if low. Inspect the starter motor and solenoid for faults | Check the battery voltage (above 12.4V for 12V systems); test wiring for shorts or opens. Verify the starter relay operation; replace if defective. Reset the fault and attempt to start. Consult the APM303 or a technician if unresolved. |
| Under speed | Generating set stops after operating correctly for at least 5 seconds due to low speed. | ensure it meets nominal RPM. Inspect the fuel system for restrictions or air. Verify the governor or throttle for proper operation. Test the speed sensor and wiring | Check the engine speed; replace if faulty. Reduce the electrical load if excessive. Reset the fault and restart. Consult the APM303 or a technician if unresolved. |
Codes and descriptions are industry-standard identifiers reproduced for identification only. This reference is not affiliated with or endorsed by SDMO; for official procedures always refer to the manufacturer’s service manual for your specific engine. A dash means our registry holds no verified entry for that column — we publish the gap rather than fill it in.
Send us the code and the engine serial. We diagnose SDMO sets on site across all 47 counties, and repair controllers at board level on the bench in Embakasi.