Updated: 2026-11-14
The reference covers 177 codes from the factory tables of Cummins ISB — the full list by system is below, stop-now codes first.
Cummins ISB is an engine with numeric codes: 86 codes in the dealer table, such as 111 and 115. The most common areas are fuel, intake air and lubrication. These are not SPNs or FMIs, so look the code up by its full number. Many codes relate to the ECM control unit, and the description often gives a sign, such as "the engine may fail to start".
Start with these codes:
This section covers the Cummins ISB engine. It is a separate block because Cummins has its own recording system: next to the J1939 pair (SPN and FMI) there is its own fault number and a lamp colour. On the KAMAZ page this engine is also mentioned separately: its codes are kept in their own block rather than mixed with the codes of the truck itself.
An engine code and a truck code can come from different controllers. If the scan tool shows the source of the code, write it down: the same number in another block can mean something else.
In a Cummins table each row holds its own fault number, an SPN, an FMI, a lamp colour and a description. Examples: fault 111 is a critical internal failure of the control module, recorded under SPN 629 and FMI 12 with a red lamp; fault 343 is a warning-level internal failure of the control module, also under SPN 629 and FMI 12. One SPN can hide several Cummins numbers, so going by SPN and FMI alone may land you on the wrong row.
And the other way round: equal digits do not mean the same fault. Cummins number 111 and SPN 111 (coolant level) are unrelated.
Cummins fault numbers are shared by several engine families: in the Cummins summary table for industrial Q-series engines, row 111 is marked for every engine in the table (QSB 6.7, QSL 9, QSX 15, QSB 4.5, QSF 3.8, QSG12). This shows the principle; for a road ISB you need the table for your own engine. Other rows, however, are marked for only some of the engines. So a code found for the ISB does not have to exist on a neighbouring engine, and the reverse.
In practice: look the code up for your own engine and module version. A neighbouring engine's table works as a hint, not as confirmation.
1. Write down the Cummins number, SPN, FMI, lamp colour and code state (active or stored).
2. Electrical FMI (3, 4, 5): connector, harness, ground at the sensor. The sensor only after that.
3. Data erratic (FMI 2) or an abnormal update rate (FMI 9): suspect the J1939 network and the power supply, not the sensor.
4. Internal failure of the control module: power, ground, fuse, module connectors. Replacing the module without this often brings the entry back.
5. Clear the codes after the repair and check for a repeat on the road.
According to Cummins, the amber lamp means service at the first opportunity and the red Stop Engine lamp means stop as soon as it is safe. The MIL lamp together with the red Stop Engine lamp also means stop and contact specialists.
If the lamp is red, do not try to limp to the workshop: continuing to drive can make the damage worse.
Match the Cummins number with the SPN in one row of one table. Do not carry a description over from another engine's table without checking the engine mark.
Record the freeze-frame and the occurrence count with the code. A code that repeats under the same conditions points to a cause; a one-off points to a random glitch.
KAMAZ, Cummins ISF, Cummins ISX
SPN 629 - controller #1, SPN 639 - J1939 network #1
A code has two halves. SPN is what is actually at fault — the sensor, component, or parameter. FMI is what is wrong with it — value out of range, open circuit, short circuit, invalid data. So “SPN 100” alone is not a diagnosis yet, but “100/1” already tells you oil pressure has dropped below normal.
That is almost always how it goes: one fault drags five or six codes behind it. An empty AdBlue tank first throws a level error, then interrupted dosing, then a NOx excess and a torque derate. Fix the root cause and the rest clear on their own. Paste the whole list — we will show which code is the root cause.
| 111 | Electronic Control Module ECM Microprocessor. Symptom: The engine may fail to start. |
| 132 | Accelerator Position Sensor Circuit. Symptom: Engine power is reduced significantly, only limp-home operation is possible. |
| 144 | Coolant Temperature Sensor Circuit |
| 191 | Air Conditioner Clutch Supply Circuit |
| 241 | Vehicle Speed Sensor Circuit. Symptom: The engine speed is limited to the upper speed limit regardless of the vehicle speed. Cruise control, protective downshift and the speed governor will not work. |
| 278 | Lift Pump Circuit |
| 298 | OEM Pressure Sensor Circuit. Symptom: Performance is not affected. |
| 364 | Electronic Control Module ECM to Pump Communications Error |
| 369 | VP44 Fuel Pump To Engine Synchronization Pulse Not Recognized |
| 377 | Fuel Pump Power Relay Stuck-On |
| 391 | VP44 Relay Coil Supply Circuit |
| 432 | Accelerator Pedal Circuit ISS. Symptom: The engine only runs at idle. |
| 443 | Accelerator Position Sensor Circuit. Symptom: The engine only stalls. |
| 524 | Switched Droop Selection Circuit |
| 141sn | Oil pressure sensor circuit |
Problem pages that cover codes of this make.
No. The Cummins number is its own; the SPN is from J1939. In a Cummins table they sit in separate columns next to the FMI and the lamp colour.
Look at the FMI and the description in the row. For example, SPN 629 with FMI 12 occurs for different control module faults, and it is the Cummins number that tells them apart.
As a hint, yes. As confirmation, no: some rows are marked for only some engines.
Know the code number? Type it into the search — or paste the whole list from the scanner and we will show which fault is the real one.