MOST COMMON DEF RELATED CODES IN DIESEL ENGINES

/ Semi Truck Def Related Error Codes , / By
  1. SPN 4364 / FMI 18:
    • Description: DEF dosing valve is not responding.
    • Possible Solution: Check the DEF dosing valve for proper operation, repair or replace if necessary.
  2. SPN 5246 / FMI 0:
    • Description: DEF tank temperature sensor circuit fault.
    • Possible Solution: Inspect DEF tank temperature sensor wiring and connections, replace if needed.
  3. SPN 5246 / FMI 15:
    • Description: DEF tank temperature high.
    • Possible Solution: Check for DEF contamination or high ambient temperatures, ensure proper DEF quality.
  4. SPN 5746 / FMI 0:
    • Description: DEF dosing valve air pressure circuit fault.
    • Possible Solution: Inspect air pressure system, repair or replace components as necessary.
  5. SPN 5746 / FMI 10:
    • Description: DEF dosing valve air pressure circuit fault.
    • Possible Solution: Check for air pressure issues, repair or replace components as needed.
  6. SPN 4334 / FMI 18:
    • Description: DEF pressure too high.
    • Possible Solution: Inspect DEF pressure regulation system, check for blockages, repair or replace components.
  7. SPN 4335 / FMI 0:
    • Description: DEF pump pressure too low.
    • Possible Solution: Check DEF pump operation, inspect for blockages, replace DEF pump if necessary.
  8. SPN 4335 / FMI 18:
    • Description: DEF pump pressure circuit fault.
    • Possible Solution: Inspect DEF pump pressure circuit, repair or replace components as needed.
  9. SPN 3364 / FMI 2:
    • Description: Poor DEF quality.
    • Possible Solution: Service DEF and filter, check for contamination, ensure proper DEF quality.
  10. SPN 3364 / FMI 3:
    • Description: DEF tank level sensor circuit fault.
    • Possible Solution: Inspect DEF tank level sensor wiring and connections, replace if needed.
  11. SPN 3364 / FMI 17:
    • Description: DEF tank temperature sensor circuit fault.
    • Possible Solution: Inspect DEF tank temperature sensor wiring, repair or replace as necessary.
  12. SPN 3364 / FMI 18:
    • Description: DEF tank level high.
    • Possible Solution: Check for overfilling, drain excess DEF if necessary.
  13. SPN 3364 / FMI 18:
    • Description: DEF tank level low.
    • Possible Solution: Check DEF level, refill if low, inspect for leaks.
  14. SPN 3364 / FMI 21:
    • Description: DEF quality low.
    • Possible Solution: Service DEF, check for contamination, ensure proper DEF quality.
  15. SPN 3364 / FMI 31:
    • Description: DEF quality circuit fault.
    • Possible Solution: Inspect DEF quality circuit, repair or replace components as needed.
  16. SPN 5397 / FMI 10:
    • Description: DEF concentration sensor circuit fault.
    • Possible Solution: Inspect DEF concentration sensor wiring, repair or replace components as necessary.
  17. SPN 5397 / FMI 15:
    • Description: DEF concentration sensor circuit fault.
    • Possible Solution: Check DEF concentration sensor wiring, repair or replace components as needed.
  18. SPN 5397 / FMI 31:
    • Description: DEF concentration circuit fault.
    • Possible Solution: Inspect DEF concentration circuit, repair or replace components as needed.
  19. SPN 5848 / FMI 16:
    • Description: DEF tank level sensor circuit fault.
    • Possible Solution: Inspect DEF tank level sensor wiring, repair or replace components as needed.
  20. SPN 5848 / FMI 17:
    • Description: DEF tank level sensor circuit fault.
    • Possible Solution: Check DEF tank level sensor wiring, repair or replace components as necessary.
  1. SPN 5397 / FMI 7:
  • Description: DEF concentration too low during a diesel particulate filter (DPF) regen.
  • Possible Solution: Check DEF concentration, service DEF if necessary, monitor during DPF regen.
  1. SPN 5397 / FMI 9:
  • Description: DEF concentration too high during a DPF regen.
  • Possible Solution: Verify DEF concentration, service DEF if needed, monitor during DPF regen.
  1. SPN 3364 / FMI 13:
  • Description: DEF tank level sensor not responding.
  • Possible Solution: Inspect DEF tank level sensor, repair or replace as necessary.
  1. SPN 4364 / FMI 1:
  • Description: DEF dosing valve circuit failed low.
  • Possible Solution: Inspect DEF dosing valve circuit, repair or replace components as needed.
  1. SPN 4364 / FMI 13:
  • Description: DEF dosing valve not responding.
  • Possible Solution: Check DEF dosing valve for proper operation, repair or replace if necessary.
  1. SPN 4364 / FMI 14:
  • Description: DEF dosing valve circuit failed high.
  • Possible Solution: Inspect DEF dosing valve circuit, repair or replace components as needed.
  1. SPN 3556 / FMI 4:
  • Description: Diesel Oxidations Catalyst (DOC) inlet temperature sensor circuit fault.
  • Possible Solution: Inspect DOC inlet temperature sensor circuit, repair or replace components as necessary.
  1. SPN 3556 / FMI 5:
  • Description: DOC inlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DOC components, repair or replace if needed.
  1. SPN 3556 / FMI 7:
  • Description: DOC inlet temperature sensor not responding.
  • Possible Solution: Inspect DOC inlet temperature sensor, repair or replace as necessary.
  1. SPN 3556 / FMI 8:
  • Description: Diesel Particulate Filter (DPF) outlet temperature sensor circuit fault.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as needed.
  1. SPN 3556 / FMI 10:
  • Description: DPF outlet temperature sensor not responding.
  • Possible Solution: Inspect DPF outlet temperature sensor, repair or replace as necessary.
  1. SPN 3556 / FMI 11:
  • Description: DPF outlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DPF components, repair or replace if needed.
  1. SPN 3556 / FMI 12:
  • Description: DPF outlet temperature sensor circuit failed low.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as necessary.
  1. SPN 3556 / FMI 13:
  • Description: DPF outlet temperature sensor circuit failed high.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as needed.
  1. SPN 3556 / FMI 16:
  • Description: DPF inlet temperature sensor circuit fault.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as necessary.
  1. SPN 3556 / FMI 17:
  • Description: DPF inlet temperature sensor not responding.
  • Possible Solution: Inspect DPF inlet temperature sensor, repair or replace as necessary.
  1. SPN 3556 / FMI 18:
  • Description: DPF inlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DPF components, repair or replace if needed.
  1. SPN 3556 / FMI 19:
  • Description: DPF inlet temperature sensor circuit failed low.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as necessary.
  1. SPN 3556 / FMI 20:
  • Description: DPF inlet temperature sensor circuit failed high.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as needed.
  1. SPN 5246 / FMI 16:
  • Description: DEF tank level sensor not responding.
  • Possible Solution: Inspect DEF tank level sensor, repair or replace as necessary.

41. SPN 5397 / FMI 7:

  • Description: DEF concentration too low during a diesel particulate filter (DPF) regen.
  • Possible Solution: Check DEF concentration, service DEF if necessary, monitor during DPF regen.

42. SPN 5397 / FMI 9:

  • Description: DEF concentration too high during a DPF regen.
  • Possible Solution: Verify DEF concentration, service DEF if needed, monitor during DPF regen.

43. SPN 3364 / FMI 13:

  • Description: DEF tank level sensor not responding.
  • Possible Solution: Inspect DEF tank level sensor, repair or replace as necessary.

44. SPN 4364 / FMI 1:

  • Description: DEF dosing valve circuit failed low.
  • Possible Solution: Inspect DEF dosing valve circuit, repair or replace components as needed.

45. SPN 4364 / FMI 13:

  • Description: DEF dosing valve not responding.
  • Possible Solution: Check DEF dosing valve for proper operation, repair or replace if necessary.

46. SPN 4364 / FMI 14:

  • Description: DEF dosing valve circuit failed high.
  • Possible Solution: Inspect DEF dosing valve circuit, repair or replace components as needed.

47. SPN 3556 / FMI 4:

  • Description: Diesel Oxidations Catalyst (DOC) inlet temperature sensor circuit fault.
  • Possible Solution: Inspect DOC inlet temperature sensor circuit, repair or replace components as necessary.

48. SPN 3556 / FMI 5:

  • Description: DOC inlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DOC components, repair or replace if needed.

49. SPN 3556 / FMI 7:

  • Description: DOC inlet temperature sensor not responding.
  • Possible Solution: Inspect DOC inlet temperature sensor, repair or replace as necessary.

50. SPN 3556 / FMI 8:

  • Description: Diesel Particulate Filter (DPF) outlet temperature sensor circuit fault.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as needed.

51. SPN 3556 / FMI 10:

  • Description: DPF outlet temperature sensor not responding.
  • Possible Solution: Inspect DPF outlet temperature sensor, repair or replace as necessary.

52. SPN 3556 / FMI 11:

  • Description: DPF outlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DPF components, repair or replace if needed.

53. SPN 3556 / FMI 12:

  • Description: DPF outlet temperature sensor circuit failed low.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as necessary.

54. SPN 3556 / FMI 13:

  • Description: DPF outlet temperature sensor circuit failed high.
  • Possible Solution: Inspect DPF outlet temperature sensor circuit, repair or replace components as needed.

55. SPN 3556 / FMI 16:

  • Description: DPF inlet temperature sensor circuit fault.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as necessary.

56. SPN 3556 / FMI 17:

  • Description: DPF inlet temperature sensor not responding.
  • Possible Solution: Inspect DPF inlet temperature sensor, repair or replace as necessary.

57. SPN 3556 / FMI 18:

  • Description: DPF inlet temperature high.
  • Possible Solution: Check for overheat conditions, inspect DPF components, repair or replace if needed.

58. SPN 3556 / FMI 19:

  • Description: DPF inlet temperature sensor circuit failed low.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as necessary.

59. SPN 3556 / FMI 20:

  • Description: DPF inlet temperature sensor circuit failed high.
  • Possible Solution: Inspect DPF inlet temperature sensor circuit, repair or replace components as needed.

60. SPN 5246 / FMI 16:

  • Description: DEF tank level sensor not responding.
  • Possible Solution: Inspect DEF tank level sensor, repair or replace as necessary.

Regular maintenance, prompt diagnosis, and professional assistance contribute to efficient diesel engine performance. Always consult with a qualified technician for comprehensive troubleshooting and repairs.