SPN 639 — J1939 Network #1
Safe to driveEnough to reach the yard
J1939 code SPN 639. Below — how the fault is worded at the factory by Bendix ABS/ESP, DAF, Dongfeng, Foton, International, Isuzu, KAMAZ, Knorr-Bremse EBS, MAN, MAZ, Mercedes-Benz, Meritor (ex-WABCO), Renault Trucks, SITRAK, WABCO ABS/ESC and YaMZ, and what the second half of the code (FMI) means in the standard.
Bendix ABS/ESPDAFDongfengFotonInternationalIsuzuKAMAZKnorr-Bremse EBSMANMAZMercedes-BenzMeritor (ex-WABCO)Renault TrucksSITRAKWABCO ABS/ESCYaMZ
Bendix ABS/ESP
| FMI 2 | J1939 Engine Communications; J1939 Invalid Data (Engine/Retarder); J1939 Supply Pressure; J1939 ESP Messages Invalid Data; Timeout or invalid data on ETC7/VP15 (for HSA-function); timeout or invalid data on XBR; Invalid Data From Transmisson; J1939 HSA switch error or unavailable; timeout or invalid data for ESP AWD operation |
| FMI 12 | J1939 Serial Link |
| FMI 14 | J1939 Retarder |
DAF
| FMI 9 | CAN connection no communication |
| FMI 13 | CAN connection network communication error |
Dongfeng
| FMI 2 | CAN1 bus open circuit. Effect: ABS/ESC functions limited, amber lamp on. |
| FMI 9 | J1939 bus message timeout |
| FMI 13 | Incorrect messages on the J1939 bus |
Foton
| FMI 9 | Lost communication with engine control unit |
International
| FMI 2 | Drivetrain Message Timeout — EEPROM data in the Microcontroller is corrupted or Error in Calibration (The Compass module is not calibrated.) |
| FMI 9 | Drivetrain Message Timeout — J1939 Communication Link Fault; Drivetrain Message Timeout — J1939 Drivetrain Data Link Lost |
| FMI 14 | Drivetrain Message Timeout — Failed to receive PGN 65535.; Drivetrain Message Timeout — Communication fault (from PP3 to ESC) |
| FMI 19 | Drivetrain Message Timeout — HMC6352 sensor is not responding or communication link with HMC6352 (I2C communication link) not working reliably. |
Isuzu
| FMI 2 | CAN Bus fault (U2104) |
| FMI 3 | CAN timeout fault (U2106) |
KAMAZ
| FMI 2 | SAE J1939 data link. K-line code on KamAZ-5490: ADM3 14902. |
| FMI 12 | ⚠ CAN bus A off-line (bus-off) |
Knorr-Bremse EBS
| FMI 4 | Channel J1939 data CAN transmission. No signal |
| FMI 10 | Channel data J1939, CAN powertrain. Open |
MAN
| FMI 4 | Channel J1939 data CAN transmission - No signal |
| FMI 10 | Channel J1939 data CAN powertrain - Open |
MAZ
| FMI 12 | CAN line A missing - Bus disconnected. Blink code: 4-1-1. Repair: Check the CAN bus connection to the other CAN devices. |
Mercedes-Benz
| FMI 13 | HDMS Fan is configured and the J1939 message was not received or has stopped arriving |
| FMI 14 | J1939 Data Link Failure (CPC is no longer sending or receiving data from the J1939 link.) |
Meritor (ex-WABCO)
| FMI 12 | BusOffError on VMM- CAN |
Renault Trucks
| FMI 2 | CAN line open or shorted, or timeout on the transmission message. Repair: Check the continuity of the CAN bus connected to the EBS unit (X1/1, X1/3). Check that the retarder control unit sends its signal over the CAN data bus. Check the continuity of the CAN bus wiring (X1/1, X1/2). |
| FMI 5 | CAN data bus fault detected. Repair: Communication failure between the gearbox and the engine brake (J 2/8, J 2/39). |
| FMI 8 | CAN bus fault — short or open circuit, no communication. Repair: No response from the VECU. Check the CAN data bus (J 2/8, J 2/39). Check the wiring (J 2/8, J 2/39). Communication failure between the ABS and the engine (J 2/8, J 2/39). Communication failure between the ABS and the engine brake (J 2/8, J 2/39). Communication failure between the VECU and the engine (J 2/8, J 2/39). Communication failure between the engine and the intarder (J 2/8, J 2/39). Communication failure between the gearbox and the engine (J 2/8, J 2/39). |
| FMI 9 | No CAN communication between the VECU and the engine (the ASTRONIC lever included). Repair: Run the diagnostic check of the system, check the CAN bus connections; the resistance between the two wires must be 60 ohms. Check the continuity of the CAN bus connected to the EBS unit (X1/1, X1/3). Check the CAN data bus. The link between the VECU and the engine (B 8, B 39). Make sure the tachograph works correctly. Make sure the connection between the tachograph and the VECU is correct. Make sure the CAN bus works correctly, check the continuity and insulation of the wiring (SL3/3, SL3/4, SL3/6, SL3/7). |
| FMI 12 | Loss of communication with the CAN data bus. Repair: Check the continuity of the CAN bus wiring connected to the ABS unit (X1/1, X1/2). |
SITRAK
| FMI 12 | CAN1 broadcast message error |
| FMI 13 | CAN1 address conflict |
WABCO ABS/ESC
| FMI 2 | SAE J1939 Data Link VSC1 Speed Erratic, Intermittent or Incorrect |
| FMI 5 | SAE J1939 Data Link Open or Short Circuit |
| FMI 6 | SAE J1939 No Access |
| FMI 9 | SAE J1939 Data Link EEC1 Timeout |
| FMI 10 | SAE J1939 XBR Timeout Temporary |
| FMI 12 | SAE J1939 Internal Error |
| FMI 13 | SAE J1939 XBR Timeout Temporary |
| FMI 14 | SAE J1939 Data Link ESC1 Timeout |
YaMZ
| FMI 12 | CAN line A missing (Bus disconnected). Blink code: 4-1-1. Repair: Check the CAN bus connection to the other CAN devices. |
What FMI means in J1939
| SPN 639 FMI 2639/2 · 639.2 | data erratic or intermittent |
| SPN 639 FMI 3639/3 · 639.3 | voltage above normal or shorted high |
| SPN 639 FMI 4639/4 · 639.4 | voltage below normal or shorted to ground |
| SPN 639 FMI 5639/5 · 639.5 | current below normal or open circuit |
| SPN 639 FMI 6639/6 · 639.6 | current above normal or grounded circuit |
| SPN 639 FMI 8639/8 · 639.8 | abnormal frequency or pulse width |
| SPN 639 FMI 9639/9 · 639.9 | abnormal update rate |
| SPN 639 FMI 10639/10 · 639.10 | abnormal rate of change |
| SPN 639 FMI 12639/12 · 639.12 | faulty device or component |
| SPN 639 FMI 13639/13 · 639.13 | calibration out of range |
| SPN 639 FMI 14639/14 · 639.14 | manufacturer-specific instructions |
| SPN 639 FMI 19639/19 · 639.19 | error in received network data |
Can I keep driving
Safe to drive. Below — how much time you have and what happens if you keep going.
What happens if you keep driving
Time you have: Enough to reach the yardThe modules have stopped hearing each other on the bus. Some dash readings are now made up and some functions are simply off.
You can physically drive, but do not trust the instruments, and the other codes in the list may well be false: fix the bus first, then look at the rest.
What to check on the spot
Check connectors and the harness: a broken CAN twisted pair takes out communication for every ECU at once.
Which codes follow
These normally light up after this code:
They are not fixed separately — they go out together with this one. The list is deliberately short: only the links the reference is sure about.
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.