Q: What does CAT fault code SPN 111 FMI 1 mean?

SPN 111 FMI 1: Warning light/Buzzer; Engine shutdown protection active; Potential coolant spray. Fix: Engine Coolant Level - Low (Most Severe). LOGIC: The level sensor (usually ultrasonic or conductivity) is not submerged. ACTION: 1. Check expansion tank level visually. 2. If tank is full, unplug sensor; check for debris/film on the sensor probe. 3. Check for air pockets in the cooling system (air lock). FIX: Top up coolant; replace Coolant Level Sensor if it fails to detect fluid.

Q: What does CAT fault code SPN 1569 FMI 31 mean?

SPN 1569 FMI 31 (Engine Control): Engine Protection Derate. Fix: LOGIC: This is a "Ghost Code" triggered by another fault. ACTION: Do not troubleshoot 1569. Find the active sensor code (like high temp or low oil) and fix that first.

Q: What does CAT fault code SPN 1569 FMI 31 mean?

SPN 1569 FMI 31 (Engine Control): Engine Derate (Power Loss) Fix: LOGIC: Fuel Leakage or High Pressure Common Rail (HPCR) Pressure Deviation. ACTION: Inspect for external fuel leaks. Check the fuel rail pressure sensor for erratic signals.

Q: What does CAT fault code SPN 168 FMI 1 mean?

SPN 168 FMI 1 (Electrical): Slow Crank / ECM Reset Fix: LOGIC: System Voltage Low (<9V). ACTION: Load test batteries. Check alternator S-terminal.

Question 1

What does CAT fault code CA428 mean?

Accepted Answer

CA428 (Fuel): Water in Fuel lamp; Rough running. Fix: WIF Sensor High Voltage.

LOGIC: Sensor circuit sees >4.5V (saturated).

ACTION: Drain water separator.

FIX: Drain bowl; replace WIF sensor.

Question 2

What does CAT fault code E157-2 mean?

Accepted Answer

E157-2 (Fuel System): Engine Stalling / High Load Fix: LOGIC: Fuel Rail Pressure Deviation.

ACTION: Check the fuel priming pump check valve for debris.

Question 3

What does CAT fault code SPN 100 FMI 3 mean?

Accepted Answer

SPN 100 FMI 3: Low oil pressure warning on dash; Possible engine derate; Gauge pinned to maximum or reading zero. Fix: LOGIC: Open circuit/Short to 5V.

ACTION: Check oil level. Unplug sensor; verify 5V ref and ground. Jumper Signal to Ground to check for FMI 4 transition.

FIX: Replace sensor or repair harness break near engine block.

Question 4

What does CAT fault code SPN 101 FMI 15 mean?

Accepted Answer

SPN 101 FMI 15 (Engine): Oil Leaking from Breather. Fix: LOGIC: High Crankcase Pressure.

ACTION: Change the Crankcase Breather Filter (Coalescer). Check for excessive "Blow-by."

Question 5

What does CAT fault code SPN 102 FMI 3 mean?

Accepted Answer

SPN 102 FMI 3: Low power; Excessive black smoke; Poor throttle response; "Lazy" turbo feel. Fix: Intake Manifold Pressure Voltage High

LOGIC: Boost signal wire open or shorted to 5V.

ACTION: Inspect turbo ducting for leaks. Jumper pins to check for FMI 4. Check for soot in sensor orifice.

FIX: Clean sensor port or replace Intake Pressure (Boost) Sensor.

Question 6

What does CAT fault code SPN 108 FMI 4 mean?

Accepted Answer

SPN 108 FMI 4: Engine is "lazy"; Poor fuel economy; Struggles at high altitude. Fix: Barometric Pressure Voltage Low.

LOGIC: Signal < 0.5V (Short to Ground). The ECM thinks the machine is at 15,000+ ft and cuts fuel to prevent smoke.

ACTION: 1. Unplug sensor; check if code changes to FMI 3. 
2. Check for 5V supply and ground. 
3. Ensure the sensor atmospheric vent isn't plugged with mud.

FIX: Replace Baro Sensor or repair signal wire shorted to frame.

Question 7

What does CAT fault code SPN 111 FMI 1 mean?

Accepted Answer

SPN 111 FMI 1: Warning light/Buzzer; Engine shutdown protection active; Potential coolant spray. Fix: Engine Coolant Level - Low (Most Severe).

LOGIC: The level sensor (usually ultrasonic or conductivity) is not submerged.

ACTION: 1. Check expansion tank level visually. 
2. If tank is full, unplug sensor; check for debris/film on the sensor probe. 
3. Check for air pockets in the cooling system (air lock).

FIX: Top up coolant; replace Coolant Level Sensor if it fails to detect fluid.

Question 8

What does CAT fault code SPN 1569 FMI 31 mean?

Accepted Answer

SPN 1569 FMI 31 (Engine Control): Engine Protection Derate. Fix: LOGIC: This is a "Ghost Code" triggered by another fault.

ACTION: Do not troubleshoot 1569. Find the active sensor code (like high temp or low oil) and fix that first.

Question 9

What does CAT fault code SPN 1569 FMI 31 mean?

Accepted Answer

SPN 1569 FMI 31 (Engine Control): Engine Derate (Power Loss) Fix: LOGIC: Fuel Leakage or High Pressure Common Rail (HPCR) Pressure Deviation.

ACTION: Inspect for external fuel leaks. Check the fuel rail pressure sensor for erratic signals.

Question 10

What does CAT fault code SPN 168 FMI 1 mean?

Accepted Answer

SPN 168 FMI 1 (Electrical): Slow Crank / ECM Reset Fix: LOGIC: System Voltage Low (<9V).

ACTION: Load test batteries. Check alternator S-terminal.

Code	System	Symptom	Full fix
CA428	Fuel	Water in Fuel lamp; Rough running.	View fix
E157-2	Fuel System	Engine Stalling / High Load	View fix
SPN 100 FMI 3	—	Low oil pressure warning on dash; Possible engine derate; Gauge pinned to maximum or reading zero.	View fix
SPN 101 FMI 15	Engine	Oil Leaking from Breather.	View fix
SPN 102 FMI 3	—	Low power; Excessive black smoke; Poor throttle response; "Lazy" turbo feel.	View fix
SPN 108 FMI 4	—	Engine is "lazy"; Poor fuel economy; Struggles at high altitude.	View fix
SPN 111 FMI 1	—	Warning light/Buzzer; Engine shutdown protection active; Potential coolant spray.	View fix
SPN 1569 FMI 31	Engine Control	Engine Protection Derate.	View fix
SPN 1569 FMI 31	Engine Control	Engine Derate (Power Loss)	View fix
SPN 168 FMI 1	Electrical	Slow Crank / ECM Reset	View fix
SPN 168 FMI 2	—	Lights flickering; Radio resetting; Random "ghost" codes across different systems; Hard starting.	View fix
SPN 177 FMI 0	—	Erratic shifting; Transmission slipping; "Hot oil" smell; Warning light on dash.	View fix
SPN 190 FMI 0	Engine	Logging / Overspeed	View fix
SPN 639 FMI 9	—	Multiple gauges "dropping out"; Engine may stay at idle; Machine won't move; Multiple controllers "Timed Out."	View fix
SPN 94 FMI 3	—	Engine "stumble" under load; Hard starting; Low power.	View fix

CAT Fault Codes

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