MTU 12V4000 G23 troubleshooting: 79 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
MTU 12V4000 G23 — full specs, parts & maintenance.
| Code | Meaning | Remedy |
|---|---|---|
| 003 | Preliminary warning: fuel temperature too high. | Contact Service. |
| 004 | Main warning: fuel temperature too high; engine stop. | Contact Service. |
| 005 | Preliminary warning: charge-air temperature too high. | Reduce power. Check intercooler. |
| 006 | Main warning: charge-air temperature too high; engine stop. | Reduce power. Check intercooler. |
| 009 | Preliminary warning: coolant Intercooler temperature in intercooler too low. | Reduce power. |
| 010 | Main warning: charge-air coolant temperature too high; engine stop. | Reduce power. |
| 015 | Preliminary warning: lube oil pressure too low. | Check oil level, top up as necessary (— Page 146). |
| 270 SO | Frequency Input SD alarm configuration; frequency input faulty; short circuit or wire break. | 1. Check cabling. 2. Check setpoint speed transmitter. |
| 361 AL | Power Stage Low SD alarm configuration; internal electronic fault (electronics possibly faulty: start ITS). If the ITS diagnosis result is “electronics OK | 1. Check solenoid valve cabling. 2. Replace ECU. |
| 362 AL | Power Stage High SD alarm configuration; internal electronic fault (electronics possibly faulty: start ITS). If the ITS diagnosis result is “electronics OK | 1. Check solenoid valve cabling. 2. Replace ECU. |
| 363 AL | Stop Power Stage SD alarm configuration; internal electronic fault (electronics possibly faulty: start ITS). If the ITS diagnosis result is “electronics OK | 1. Check cabling. 2. Attempt to restart engine. |
| 365 AL | Stop MV-Wiring SD alarm configuration; injector Ground cabling fault. If bit"1.1020.021” is set, engine will be shut down as additional measure. | 1. Check cabling. 2. Attempt to restart engine. |
| 371 AL | Wiring TO 1 SD alarm configuration; short circuit or wire break on turbocharger transistor output 1 (TO 1). | 1. Check turbocharger valve/cabling, repair as necessary. 2. Replace ECU. |
| 372 AL | Wiring TO 2 SD alarm configuration; short circuit or wire break on recirculation transistor output 2 (TO 2). | 1. Check turbocharger valve/cabling, repair as necessary. 2. Replace ECU. |
| 373 AL | Wiring TO 3 SD alarm configuration; short circuit or wire break on transistor output 3 (TO 3) | |
| 005 | Charge-air temperature too high (1st limit value) | Reduce power. Change over to idle and contact Service. |
| 006 | Charge-air temperature too high (2nd limit value) | Reduce power. Change over to idle and contact Service. |
| 009 | Charge-air coolant temperature T-INTERCOOLER too high (1st limit value) | Reduce power. Change over to idle and contact Service. |
| 015 | Lube oil pressure too low (1st limit value) | Check engine-oil level and top up, if required |
| 016 | Lube oil pressure too low (2nd limit value) | Check engine-oil level and top up, if required automatic engine shutdown Try to re-start the engine Contact Service. |
| 023 | Engine coolant level too low LEVEL (— Page 153) | Check coolant level and top up, if required |
| 030 | Engine overspeed; automatic engine shutdown | Acknowledge alarm. Try to re-start the engine Contact Service. |
| 044 | Charge-air coolant level too low INTERCOOLER (1st limit value) | Check coolant level and top up, if required |
| 045 | Charge-air coolant level too low INTERCOOLER (2nd limit value) | Check coolant level and top up, if required If fault occurs repeatedly: Contact Service. |
| 051 | Lube oil temperature too high (1st limit value) | Reduce power. Change over to idle and contact Service. |
| 052 | Lube oil temperature too high (2nd limit value) | Reduce power. Change over to idle and contact Service. If fault occurs repeatedly: Contact Service. |
| 065 | Fuel supply pressure too low (ist limit value) | Check fuel lines for leaks; repair defective lines. Clean fuel prefilter Flush fuel prefilter Replace filter element of fuel prefilter Replace fuel filter If fault is not rectified: Contact Service. |
| 066 | Fuel supply pressure too low (2nd limit value) | Check fuel lines for leaks; repair defective lines. Clean fuel prefilter Flush fuel prefilter Replace filter element of fuel prefilter Replace fuel filter If fault is not rectified: Contact Service. |
| 067 | Coolant temperature too high (tst limit value) | Reduce power. Change over to idle and warning contact Service. |
| 068 | Coolant temperature too high (2nd limit value) | Allow the engine to cool down. Check coolant cooler (elements etc.) clean contaminated parts (see manufacturer’s documentation). Re-start the engine If fault occurs repeatedly: Contact Service. |
| 069 | Violation of first limit for external temperature channel 1 point, which is read via CAN bus | |
| 070 | Violation of second limit for external temperature channel 1 point, which is read via CAN bus | |
| 071 | Violation of first limit for external temperature channel 2 | (Depending on the corresponding measuring point, which is read via CAN bus) | |
| 072 | Violation of second limit for external temperature channel 2 point, which is read via CAN bus | |
| 073 | Violation of first limit for external pressure channel 1 point, which is read via CAN bus | |
| 074 | Violation of second limit for external pressure channel 1 point, which is read via CAN bus | |
| 075 | Violation of first limit for external pressure channel 2 point, which is read via CAN bus | |
| 076 | Violation of second limit for external pressure channel 2 point, which is read via CAN bus | |
| 019 | HI T-Exhaust A | Check cabling. Contact Service. |
| 020 | SS T-Exhaust A | Check cabling. Contact Service. |
| 021 | HI T-Exhaust B | Check cabling. Contact Service. |
| 022 | SS T-Exhaust B | Check cabling. Contact Service. |
| 024 | SS Coolant Level | Check coolant level. |
| 025 | HI P-Diff. Lube Oil | Replace oil filter. |
| 026 | HI P-Diff. Lube Oil | Replace oil filter. |
| 027 | HI Leak Fuel Level | Check fuel system. Contact Service. |
| 029 | HI ETC 2 idle speed | Contact Service. |
| 031 | HI ETC 1 overspeed | Contact Service. |
| 032 | SS ETC 1 overspeed | Reduce power. Check air filters. |
| 036 | HI ETC 2 overspeed | Reduce power. Contact Service. |
| 037 | SS ETC 2 overspeed | Reduce power. Contact Service. |
| 038 | AL ETC Synchro Fault | Reduce power. Contact Service. |
| 039 | AL ETC 2 cut-in failure | Reduce power. Contact Service. |
| 057 | LO P-Coolant | Check coolant circuit. |
| 058 | SS P-Coolant | Automatic shutdown. Check coolant level. |
| 063 | HI P-Crankcase | Reduce power. Replace oil separator element. |
| 064 | SS P-Crankcase | Replace oil separator element. Contact Service. |
| 087 | AL Rail Leakage | Contact Service. |
| 082 | HI P-Fuel (Common Rail pressure > reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. | Contact Service. |
| 083 | LO P-Fuel (Common Rail pressure < reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. | Contact Service. |
| 084 | HI P-Fuel (Common Rail pressure > reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. | Contact Service. |
| 085 | LO P-Fuel (Common Rail pressure < reference value; DBR fuel limitation, start of injection readjusted towards late; suction restrictor of HP fuel block jamming or HP fuel control block wiring faulty. | Contact Service. |
| 090 | SS No Idling Speed | Contact Service. |
| 091 | SS No Runup Speed | Contact Service. |
| 092 | SS No Starter Speed | Contact Service. |
| 093 | SS T-Preheat | Check preheater. |
| 094 | LO T-Preheat | Check preheater. |
| 095 | AL Prelubrication Fault | Check oil priming system. |
| 102 | Consumption Meter Faulty | Contact Service. |
| 104 | Eng Hours Counter Defect | Contact Service. |
| 118 | LO ECU Supply Voltage | Check ECU supply voltage. Contact Service. |
| 119 | LOLO ECU Supply Voltage | Check ECU supply voltage. Contact Service. |
| 120 | HI ECU Supply Voltage | Check ECU supply voltage. Contact Service. |
| 121 | HIH] ECU Supply Voltage | Check ECU supply voltage. Contact Service. |
| 134 | 15V POS ECU DEFECT | Replace ECU. |
| 136 | 15V NEG ECU DEFECT | Contact Service. |
| 142 | BANK1 ECU DEFECT | Replace ECU. |
| 144 | BANK2 ECU DEFECT | Replace ECU. |
| 150 | Li AD-TEST3 SUPPLY | Replace ECU. |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.