SPN 609 — Controller #2
Drive with cautionEnough to reach the yard
Updated: 2026-11-14
J1939 code SPN 609. Below — how the fault is worded at the factory by KAMAZ-5490, Knorr-Bremse EBS, MAN, Mercedes-Benz and Renault Trucks, and what the second half of the code (FMI) means in the standard.
How to check it yourself
Controller No. 2 — an internal fault in the second unit in the system (on different makes this is a different unit: a second processor, a body unit, a gearbox unit). Check it the same way as controller No. 1 (SPN 629).
What it should read
| Supply at the unit connector under load | as at the battery, sag not more than 0.5 V |
Check order
- Find out from the factory description which unit is this make's "controller No. 2".
- Its power, grounds and connectors.
- The link between the units — if the code comes with FMI 9 or 19, it is lost messages, not a breakdown.
- Update the software, then replace.
Common causes — from most to least frequent
- Power or ground of the unit.
- Link between the units.
- Faulty unit.
KAMAZ-5490Knorr-Bremse EBSMANMercedes-BenzRenault Trucks
KAMAZ-5490 (Mercedes, K-line)
FMI is per the block maker's own table, not the J1939 table below.
| FMI 0 | Immobilizer: more than 8 immobilizer keys programmed. K-line code on KamAZ-5490: MR2 19960. |
| FMI 2 | Engine control unit PLD/MR2: unknown cause (ADM3 12002); Immobilizer: TPC immobilizer reports CAN error (MR2 19963); Immobilizer: wrong immobilizer key (MR2 19965). K-line code on KamAZ-5490. |
| FMI 9 | Immobilizer: TPC immobilizer reports starter circuit fault. K-line code on KamAZ-5490: MR2 19964. |
| FMI 11 | Engine control unit PLD/MR2: control unit data tampered (MR2 14056); Engine control unit PLD/MR2: data substitution, control module software error (MR2 14058); Immobilizer: immobilizer activated automatically (MR2 19962). K-line code on KamAZ-5490. |
| FMI 12 | Barometric pressure sensor in PLD/MR2: open circuit (MR2 11315); Barometric pressure sensor in PLD/MR2: short to ground (MR2 11316); Engine control unit PLD/MR2: auxiliary 8.5 V supply fault (MR2 12401); Engine control unit PLD/MR2: general internal fault (MR2 12402); Engine control unit PLD/MR2: regulator in limp mode / regulator 2 faulty (MR2 14024); Engine control unit PLD/MR2: PVB1 high-side switch faulty (MR2 14034); Engine control unit PLD/MR2: PVB2 high-side switch faulty (MR2 14035); Engine control unit PLD/MR2: PV5 high-side switch faulty (MR2 14036); Engine control unit PLD/MR2: starter output stage damaged (backup) (MR2 14038); Engine control unit PLD/MR2: starter output stage damaged (main) (MR2 14039); Engine control unit PLD/MR2: starter diagnostics fault (MR2 14040, MR2 14041); Engine control unit PLD/MR2: CAN-L bus fault (MR2 14054); Engine control unit PLD/MR2: wrong boot block (MR2 14262); PLD/MR2 bootloader: application software faulty (MR2 14296); PLD/MR2 bootloader: flash memory faulty (MR2 14297); PLD/MR2 bootloader: flash memory cannot be erased (MR2 14298); PLD/MR2 bootloader: no application software in flash (MR2 14299); Starter relay circuit PLD/MR2: short (main or backup) (MR2 18039). K-line code on KamAZ-5490. |
| FMI 13 | Engine control unit PLD/MR2: cylinder count does not match engine. K-line code on KamAZ-5490: MR2 12400. |
| FMI 14 | PLD/MR2 software: wrong number of cylinders (MR2 14037, MR2 14048); PLD/MR2 software: wrong data card installed (MR2 14047); PLD/MR2 software: PWM calibration (MR2 14049); PLD/MR2 software: wrong hardware (MR2 14050); PLD/MR2 software: EEPROM checksum 1 (MR2 14051); PLD/MR2 software: EEPROM checksum 2 (MR2 14052); PLD/MR2 software: EEPROM checksum 3 (MR2 14053); Engine control module Tier4i (Euromot3b): chassis control module mismatch (MR2 14269); Immobilizer: immobilizer counter response invalid (MR2 19961). K-line code on KamAZ-5490. |
Knorr-Bremse EBS
| FMI 0 | Central control unit in controller. Undefined fault |
MAN
| FMI 0 | Central control unit - Undefined fault |
Mercedes-Benz
| FMI 16 | Internal temperature of CPC4 too high |
Renault Trucks
| FMI 2 | EECU internal fault. Repair: Replace the EECU control unit. |
| FMI 3 | EECU internal fault. Repair: Replace the EECU control unit. |
| FMI 6 | EECU internal fault. Repair: Replace the EECU control unit. |
| FMI 8 | EECU internal fault. Repair: Replace the EECU control unit. |
What FMI means in J1939
Can I keep driving
Drive with caution. The ABS on this wheel or axle may be off, but the service brakes work. On a slippery road brake gently. Get it repaired soon.
What happens if you keep driving
The ABS on this wheel or axle may be out of action, while the service brakes still work. On a dry road you may notice no difference.
On a slippery road brake gently and keep a longer following distance. Do not put the repair off: if the red brake lamp comes on or the pedal feels soft, stop.
Nearby: other
- SPN 527Cruise Control States
- SPN 533Maximum Momentary Override Speed, Point 7
- SPN 551Idle Torque, %, Point 1
- SPN 558Accelerator Pedal Idle Limit Switch #1
- SPN 564Inter-Axle Differential Lock Status
- SPN 611System Diagnostic Code #1
- SPN 624Yellow Warning Lamp
- SPN 630Calibration Memory
- SPN 701Auxiliary Input/Output #01
- SPN 705Auxiliary Input/Output #05
Related codes
- SPN 706Auxiliary Input/Output #06
- SPN 711Auxiliary Input/Output #11
- SPN 723Engine speed (auxiliary sensor)
- SPN 746Differential Lock Solenoid Valve #1
- SPN 806ASR Valve, Differential 1
- SPN 920Audible Alarm
- SPN 925Auxiliary Output #2
- SPN 970Engine Auxiliary Shutdown Switch
Makes with this code
MANMercedes-BenzRenault TrucksKAMAZ-5490Knorr-Bremse EBS
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.