SPN 1351 — Air Compressor State
Do not driveMinutes
Updated: 2026-11-14
J1939 code SPN 1351. Below — how the fault is worded at the factory by KAMAZ, MAZ, Meritor (ex-WABCO), SITRAK and YaMZ, and what the second half of the code (FMI) means in the standard.
How to check it yourself
Compressor status: the unit controls the switching off of the compressor (clutch or idle valve) and monitors the build-up of pressure.
What it should read
| Regulator cut-out pressure | usually about 8…12.5 bar — per the factory data |
| Build-up from zero to working pressure | usually a few minutes at idle — per the factory standards |
Check order
- Build-up time and cut-out pressure from the gauge on the dash.
- Slow build-up — leaks in the pneumatic system, compressor wear, a delivery pipe clogged with carbon.
- FMI 3, 4, 5, 6: the solenoid valve controlling the compressor or its clutch, and its connector.
- Air dryer: if it does not purge, the compressor works against the pressure.
Common causes — from most to least frequent
- Air leaks.
- Clogged delivery pipe.
- Compressor control valve.
- Compressor wear.
KAMAZMAZMeritor (ex-WABCO)SITRAKYaMZ
KAMAZ engine (J1939)
| FMI 2 | Air conditioning power stage |
| FMI 3 | Air conditioning power stage |
| FMI 4 | Air conditioning power stage |
| FMI 12 | Air conditioning power stage |
MAZ
| FMI 2 | A/C compressor driver circuit fault - Overheating. Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 3 | A/C compressor driver circuit fault - Short to battery positive. Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 4 | A/C compressor driver circuit fault - Short to ground. Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 12 | A/C compressor driver circuit fault - Open circuit. Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
Meritor (ex-WABCO)
| FMI 0 | EAPU - Compressor/ Overpressure Fault |
| FMI 11 | EAPU - Compressor/ Critical Air Consumption |
SITRAK
| FMI 3 | A/C compressor circuit short to battery. Scan tool code: P0647. Effect: Torque may be limited. |
| FMI 4 | A/C compressor circuit short to ground. Scan tool code: P0646. Effect: Torque may be limited. |
| FMI 5 | Open load in the A/C compressor circuit. Scan tool code: P0645. Effect: Torque may be limited. |
| FMI 6 | Over-temperature of the A/C compressor powerstage. Scan tool code: P0645. Effect: Torque limited, the engine may shut down. |
YaMZ
| FMI 2 | Air conditioning control driver circuit fault (Overheating). Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 3 | Air conditioning control driver circuit fault (Short to battery positive). Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 4 | Air conditioning control driver circuit fault (Short to ground). Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
| FMI 12 | Air conditioning control driver circuit fault (Open circuit). Blink code: 3-1-3. Repair: Check the air conditioner and its wiring. |
What FMI means in J1939
Can I keep driving
Do not drive. Stop as soon as it’s safe to do so — don’t keep going.
What happens if you keep driving
Part of the brake circuit or ABS/EBS is out of service. The pedal may still feel normal — until the first emergency stop or descent.
Next comes longer stopping distance, a skid on a slick surface, failure on a long downgrade. This is the case where "I will take it slow" does not work.
What to check on the spot
Let the air system build to working pressure and listen for leaks. Don’t drive with faulty brakes.
Nearby: brakes
- SPN 796ABS Pressure Modulator Valve, Axle 1, Right
- SPN 797ABS Pressure Modulator Valve, Axle 2, Left
- SPN 798ABS Pressure Modulator Valve, Axle 2, Right
- SPN 799ABS Pressure Modulator Valve, Axle 3, Left
- SPN 800ABS Pressure Modulator Valve, Axle 3, Right
- SPN 938Brake Release Modulator Valve Solenoid, Axle #1, Left
- SPN 939Brake Release Modulator Valve Solenoid, Axle #1, Right
- SPN 1087Service Brake Air Pressure, Circuit #1
- SPN 1121EBS Brake Switch
- SPN 1438ABS/EBS Amber Warning Signal
Related codes
- SPN 795ABS Pressure Modulator Valve, Axle 1, Left
- SPN 794ABS Wheel Speed Sensor, Axle 3, Right
- SPN 793ABS Wheel Speed Sensor, Axle 3, Left
- SPN 792ABS Wheel Speed Sensor, Axle 2, Right
- SPN 791ABS Wheel Speed Sensor, Axle 2, Left
- SPN 790ABS Wheel Speed Sensor, Axle 1, Right
- SPN 789ABS Wheel Speed Sensor, Axle 1, Left
- SPN 603Brake Pedal Switch #2
Makes with this code
Related problems
- Check Engine light is on
- Air pressure will not build
Scanner threw several codes at once? Paste the whole list — we will show which one is the root cause and which ones simply followed.