Question 1

What does Cummins fault code 1117 (SPN 627 FMI 2) mean?

Accepted Answer

1117 (SPN 627 FMI 2): Engine won't start; Sudden power loss while driving; Scanner drops connection. Fix: Power Supply Lost with Ignition On.

LOGIC: The ECM detected a loss of battery power while the "Key Switch" was still in the ON position.

ACTION: 1. Check main 30A fuses at the battery. 
2. Check the ECM power relay. 
3. Inspect main battery ground at the frame.

FIX: Tighten battery terminals; replace corroded fuses; replace ECM Power Relay.

Question 2

What does Cummins fault code 122 (SPN 102 FMI 3) mean?

Accepted Answer

122 (SPN 102 FMI 3): Significant power derate; Black smoke; Engine may feel "choked" or "lazy." Fix: Intake Manifold Pressure (Boost) Sensor - Voltage High.

LOGIC: Signal > 4.5V (Open Circuit). The ECM loses the ability to measure boost and assumes a default failed state.

ACTION: 1. Unplug sensor and Jumper Signal to Return; if code becomes 123 (FMI 4), harness is good. 
2. Verify 5V Ref on Pin A.

FIX: Replace Boost Sensor or repair broken wire in the harness loom near the intake.

Question 3

What does Cummins fault code 131 (SPN 91 FMI 3) mean?

Accepted Answer

131 (SPN 91 FMI 3): Engine stuck at idle; No throttle response; Red Stop Lamp may be active. Fix: Accelerator Pedal Position Sensor 1 - Voltage High.

LOGIC: Signal > 4.5V. Usually caused by an open return wire or a short between the 5V supply and signal wire.

ACTION: 1. Check the 6-pin pedal connector for moisture/dirt. 
2. Monitor pedal percentage on a scanner while flexing the harness near the bulkhead.

FIX: Replace Accelerator Pedal Assembly or repair wiring in the OEM cab harness.

Question 4

What does Cummins fault code 135 (SPN 100 FMI 3) mean?

Accepted Answer

135 (SPN 100 FMI 3): Oil pressure gauge pinned at max; Warning light active; No engine protection for oil pressure. Fix: Engine Oil Pressure Sensor - Voltage High.

LOGIC: Signal > 4.5V (Open Circuit). The ECM sees infinite resistance and assumes the wire is cut or the sensor failed open.

ACTION: 1. Jumper Signal to Return; if code becomes 141 (FMI 4), replace sensor. 
2. Check Pin A for 5V supply.

FIX: Replace Oil Pressure Sensor or repair the broken signal wire.

Question 5

What does Cummins fault code 145 (SPN 110 FMI 3) mean?

Accepted Answer

145 (SPN 110 FMI 3): Engine fan runs 100%; Gauge pinned at zero/cold; Engine over-fuels on hot start (black smoke). Fix: Engine Coolant Temp 1 - Voltage High.

LOGIC: Signal > 4.5V (Open Circuit). The ECM sees infinite resistance, assumes the wire is cut, and defaults to -40°F for safety.

ACTION: 1. Unplug sensor and Jumper pins A to B. If code changes to 144 (Voltage Low), harness is good. 
2. Verify 5V ref at plug. 
3. Check for pins "backed out" of the ECM connector.

FIX: Replace Coolant Temp Sensor or repair broken signal/return wire.

Question 6

What does Cummins fault code 151 (SPN 110 FMI 0) mean?

Accepted Answer

151 (SPN 110 FMI 0): Progressive engine derate; Shutdown protection active; Fan at 100%. Fix: Coolant Temperature High - Critical.

LOGIC: Temperature has exceeded the "Most Severe" limit.

ACTION: 1. Verify actual temp with an IR gun at the thermostat housing. 
2. Check radiator for "winter front" or mud blockage. 
3. Check for aerated coolant (combustion leak).

FIX: Clean radiator/CAC; replace Thermostat; replace Water Pump.

Question 7

What does Cummins fault code 153 (SPN 105 FMI 3) mean?

Accepted Answer

153 (SPN 105 FMI 3): High idle; Excessive black smoke; Cooling fan locked on 100%. Fix: Intake Manifold Air Temp - Voltage High.

LOGIC: Signal > 4.5V (Open Circuit). The ECM assumes -40°F air temp and over-fuels to compensate for "cold" air density.

ACTION: 1. Locate sensor on the intake horn. 
2. Jumper pins to check for FMI 4. 
3. Check for soot/oil buildup on sensor tip.

FIX: Replace Intake Air Temp Sensor or repair broken wiring.

Question 8

What does Cummins fault code 1896 (SPN 2791 FMI 13) mean?

Accepted Answer

1896 (SPN 2791 FMI 13): Power loss (derate); Black smoke; Rough idle; Increased soot load in DPF. Fix: EGR Valve Controller - Out of Calibration.

LOGIC: EGR Valve calibration failure. Valve cannot reach fully open or closed stops due to soot or mechanical wear.

ACTION: Inspect for carbon buildup in the valve throat. Perform "EGR Valve Calibration" test via scan tool. Check for binding.

FIX: Clean carbon from valve and seat; replace EGR Valve assembly if internal gears are stripped.

Question 9

What does Cummins fault code 2962 mean?

Accepted Answer

2962 (Emissions): High Exhaust Temp / Derate Fix: LOGIC: EGR Temperature Above Normal (Severe).

ACTION: Check the EGR cooler for internal scaling or coolant flow restriction.

Question 10

What does Cummins fault code 3226-4 mean?

Accepted Answer

3226-4 (Emissions): Active Regen Inhibited Fix: LOGIC: Outlet NOx Sensor Voltage Below Normal.

ACTION: Inspect the sensor harness for a short to ground. Measure voltage at the 4-pin connector.

Code	System	Symptom	Full fix
1117 (SPN 627 FMI 2)	—	Engine won't start; Sudden power loss while driving; Scanner drops connection.	View fix
122 (SPN 102 FMI 3)	—	Significant power derate; Black smoke; Engine may feel "choked" or "lazy."	View fix
131 (SPN 91 FMI 3)	—	Engine stuck at idle; No throttle response; Red Stop Lamp may be active.	View fix
135 (SPN 100 FMI 3)	—	Oil pressure gauge pinned at max; Warning light active; No engine protection for oil pressure.	View fix
145 (SPN 110 FMI 3)	—	Engine fan runs 100%; Gauge pinned at zero/cold; Engine over-fuels on hot start (black smoke).	View fix
151 (SPN 110 FMI 0)	—	Progressive engine derate; Shutdown protection active; Fan at 100%.	View fix
153 (SPN 105 FMI 3)	—	High idle; Excessive black smoke; Cooling fan locked on 100%.	View fix
1896 (SPN 2791 FMI 13)	—	Power loss (derate); Black smoke; Rough idle; Increased soot load in DPF.	View fix
2962	Emissions	High Exhaust Temp / Derate	View fix
3226-4	Emissions	Active Regen Inhibited	View fix
3382 (FMI 2)	Lubrication	Derate / Shutdown	View fix
5177	Turbo	Severe Derate / VGT Frozen	View fix
559 (SPN 157 FMI 18)	—	Engine bogs under load; Hard starting; Misfire; Sudden shutdown.	View fix
Cummins 111 (629-12)	Control	No Start / No Comm.	View fix
Cummins 112/113/114 (635)	Turbo	Turbo Lag / Low Boost.	View fix
Cummins 115 (190-2)	Timing	Crank, No Start.	View fix
Cummins 116 (156-3)	Fuel System	Limp Mode / Low Rail Pressure.	View fix
Cummins 117 (SPN 156 FMI 4)	—	Engine stalling; Hard start; Severe power derate; Possible white smoke.	View fix
Cummins 118 (SPN 157 FMI 3)	—	Loud engine knock; Severe power loss (Limp Mode); Check Engine Light.	View fix
Cummins 119 (SPN 135 FMI 4)	—	Low oil pressure alarm; 0 PSI on gauge; Engine may shutdown automatically.	View fix
Cummins 144 (SPN 110 FMI 4)	—	Fan stays on 100%; Gauge pinned to Hot; Hard starting in cold weather; Engine derate.	View fix
Cummins 221	Air Intake	Engine Derate / Active CEL	View fix
Cummins 3382 (SPN:100 / FMI:2)	Lubrication	Engine Derate / Warning Light	View fix
Cummins 351 (3597-12)	Power	Engine Stumbles / Dies.	View fix
Cummins 3712 (SPN:5246 / FMI:0)	Aftertreatment	Final Derate / 5 MPH Limit.	View fix
Cummins 6254 (SPN:6254 / FMI:9)	Aftertreatment	Limp Mode / Engine Derate.	View fix
FC 1922	—	Filter light flashes. If ignored, engine will severely derate and eventually "Lock Out."	View fix
FC 234	—	Engine speed has exceeded the safety threshold. Possible fuel system fault.	View fix
FC 441	—	ECM may lose communication; engine stumbles or display flickers.	View fix
P000F	Fuel System	Sudden Engine Shutdown	View fix
P00AF	Turbo	Severe Derate	View fix
P0251	Fuel System	Engine Cuts Out under Load / Misfire	View fix
P0252	Fuel System	Engine Surges under Load / Cuts Out	View fix
SPN 100 FMI 1	Lubrication	Engine Shutdown	View fix
SPN 100 FMI 2	Lubrication	Stop Engine Light	View fix
SPN 103 FMI 2	—	Turbo "whining"; Erratic boost; Low power; Whistling sound under load.	View fix
SPN 105 FMI 3	—	High idle; Excessive black smoke; Fan stays on 100% of the time.	View fix
SPN 110 FMI 0	—	Engine fan at 100% duty cycle; Significant power loss (Derate); High temp alarm; Potential engine shutdown.	View fix
SPN 111 FMI 1	Cooling	Engine Shutdown	View fix
SPN 132 FMI 2	Air Intake	Black Smoke / Engine Sags	View fix
SPN 157 FMI 1	—	Hard starting; Engine stalling under load; Misfiring; Severe power loss.	View fix
SPN 157 FMI 18	Emissions	Derate (5 mph / 8 kph). The truck is restricted to "crawl" speed.	View fix
SPN 190 FMI 0	—	High-pitched engine whine; Sudden surge in RPM; Possible "Runaway" if oil-fed; Check Engine Light.	View fix
SPN 3031 (FMI 2)	Exhaust (SCR)	Inducement / 5-MPH Derate.	View fix
SPN 3216 FMI 20	—	DEF usage is high or low; Frequent parked regens; "Derate" timer may start; Check engine light.	View fix
SPN 3216 FMI 20	Aftertreatment	Aftertreatment Derate	View fix
SPN 3216 FMI 3	Emissions	SCR Engine Derate / MIL On	View fix
SPN 3242 FMI 15	Emissions / DPF	Regen Aborted / High EGT Warning	View fix
SPN 3251 FMI 0	Aftertreatment	High DPF Differential Pressure	View fix
SPN 3251 FMI 00	Emissions / Exhaust	High Soot Level / Forced Regen Locked	View fix

Cummins Fault Codes

Ready to take control of your fleet maintenance?

Other manufacturers