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SPN 2791 — EGR Valve Control

Safe to driveEnough to reach the yard

Updated: 2026-11-14

J1939 code SPN 2791. Below — how the fault is worded at the factory by Cummins ISB, KAMAZ, KAMAZ-5490, MAZ, SITRAK and YaMZ, and what the second half of the code (FMI) means in the standard.

How to check it yourself

EGR valve control: the ECU feeds current or air to the valve actuator. The code is about this control circuit: the actuator itself, its supply, or the valve not moving where it was told.

What it should read

Electric actuator: winding resistanceper the factory data, usually from a few to tens of ohms
Pneumatic actuator: control pressureas in the pneumatic system, without leaks

Check order

  1. Valve test from diagnostics: listen to it moving.
  2. Electric actuator: connector and winding — open, and short to the body.
  3. Pneumatic actuator: the tube to the actuator, the solenoid control valve, leaks.
  4. Valve coked — the actuator cannot move it, and the ECU sees an actuator fault.
  5. If there is also a position code, SPN 27 — check the valve itself first.

Common causes — from most to least frequent

  1. Coked valve.
  2. Actuator or its connector.
  3. Pneumatic actuator: air leak.

Cummins ISBKAMAZKAMAZ-5490MAZSITRAKYaMZ

Cummins ISB 6.7 engine

FMI 5EGR valve control circuit current low or open
FMI 6EGR valve control circuit current high or grounded
FMI 13EGR valve controller out of calibration
FMI 15EGR valve control circuit calculated over-temperature, least severe

KAMAZ engine (J1939)

FMI 2EGR actuator: short circuit / open circuit / overheating.
FMI 3EGR actuator: short circuit / open circuit / overheating
FMI 4EGR actuator: short circuit / open circuit / overheating
FMI 5EGR actuator: short circuit / open circuit / overheating

KAMAZ-5490 (Mercedes, K-line)

FMI is per the block maker's own table, not the J1939 table below.

FMI 0Exhaust gas recirculation (EGR): sensor circuit open or shorted to positive. K-line code on KamAZ-5490: MR2 13215.
FMI 1Exhaust gas recirculation (EGR): sensor circuit shorted to ground. K-line code on KamAZ-5490: MR2 13216.
FMI 2EGR actuator: system performance, temperature diagnosis. K-line code on KamAZ-5490: MR2 16679.
FMI 7Exhaust gas recirculation (EGR): general system control error. K-line code on KamAZ-5490: MR2 16678.
FMI 12Exhaust gas recirculation (EGR): temperature too high / too low. K-line code on KamAZ-5490: MR2 13332.

MAZ

FMI 0EGR valve position control error - Maximum positive deviation exceeded. Blink code: 6-8-1. Repair: Check all EGR system components and their wiring.
FMI 1EGR valve position control error - Maximum negative deviation exceeded. Blink code: 6-8-1. Repair: Check all EGR system components and their wiring.
FMI 2EGR control valve fault - Overheating. Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 3EGR control valve fault - CJ230 driver error. Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 4EGR control valve fault - Valve control current exceeded. Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 7EGR valve pneumatic actuator stuck - Bypass valve stuck. Blink code: 6-7-1. Repair: Check the pneumatic actuator of the EGR flap.
FMI 12EGR control valve fault - Current limited due to overheating. Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.

SITRAK

FMI 2EGR valve command message error on the CAN bus. Scan tool code: P0403. Effect: Loss of communication with the modules, some functions are disabled.
FMI 3EGR valve power supply error. Scan tool code: P0403. Effect: Torque may be limited.
FMI 12System error in the EGR valve circuit. Scan tool code: P0403. Effect: Torque may be limited.
FMI 14EGR valve initialisation error. Scan tool code: P0400. Effect: Torque may be limited.
FMI 20High thermal load on the EGR valve powerstage in the ECU. Scan tool code: P0403. Effect: Torque limited, the engine may shut down.
FMI 21High temperature in the EGR valve control unit. Scan tool code: P040A. Effect: Fan and warm-up control may misbehave.
FMI 23EGR valve position deviation warning. Scan tool code: P0400.
FMI 24EGR valve position sensor error. Scan tool code: P0409.

YaMZ

FMI 0EGR valve position control fault (Maximum positive deviation exceeded). Blink code: 6-8-1. Repair: Check all EGR system components and their wiring.
FMI 1EGR valve position control fault (Maximum negative deviation exceeded). Blink code: 6-8-1. Repair: Check all EGR system components and their wiring.
FMI 2EGR valve control valve fault (Overheating). Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 3EGR valve control valve fault (CJ230 driver error). Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 4EGR valve control valve fault (Valve control current exceeded). Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.
FMI 7EGR valve pneumatic actuator seized (Bypass valve seized). Blink code: 6-7-1. Repair: Check the pneumatic actuator of the EGR flap.
FMI 12EGR valve control valve fault (Current limited due to overheating). Blink code: 6-6-2. Repair: Check the electropneumatic EGR flap control valve and its wiring.

What FMI means in J1939

SPN 2791 FMI 02791/0 · 2791.0data above normal range (most severe level)
SPN 2791 FMI 12791/1 · 2791.1data below normal range (most severe level)
SPN 2791 FMI 22791/2 · 2791.2data erratic or intermittent
SPN 2791 FMI 32791/3 · 2791.3voltage above normal or shorted high
SPN 2791 FMI 42791/4 · 2791.4voltage below normal or shorted to ground
SPN 2791 FMI 52791/5 · 2791.5current below normal or open circuit
SPN 2791 FMI 62791/6 · 2791.6current above normal or grounded circuit
SPN 2791 FMI 72791/7 · 2791.7mechanical system not responding
SPN 2791 FMI 122791/12 · 2791.12faulty device or component
SPN 2791 FMI 132791/13 · 2791.13calibration out of range
SPN 2791 FMI 142791/14 · 2791.14manufacturer-specific instructions
SPN 2791 FMI 152791/15 · 2791.15above normal — low severity
SPN 2791 FMI 202791/20 · 2791.20data drifted high
SPN 2791 FMI 212791/21 · 2791.21data drifted low

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 yard

Boost is not reaching its target: turbo, intercooler or intake. The engine compensates with mixture and runs hotter than usual.

You will lose pull, burn more fuel and add overheating on long climbs. If you hear a whine or a whistle from the turbo, stop — the wheel is breaking up.

This is an electrical fault: an open, a short or a bad contact in the sensor circuit. The value it measures is most likely fine. You can drive. But until the circuit is repaired this system runs blind and cannot warn you about a real failure.

What to check on the spot

Inspect the air filter and charge-air hoses: leaks and cracks produce exactly these codes.

Where to start

This code is often not the fault itself but a knock-on. If any of these is in the same readout, start with it:

Nearby: intake / boost

Makes with this code

KAMAZMAZYaMZSITRAKCummins ISBKAMAZ-5490

Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.