Cummins Fault Code
Free · no signupSPN 103 FMI 2
Turbo "whining"; Erratic boost; Low power; Whistling sound under load.
System
Not specified
Symptom
Turbo "whining"; Erratic boost; Low power; Whistling sound under load.
Diagnosis & fix steps
Turbocharger 1 Speed - Data Erratic.
LOGIC: The turbo speed sensor signal is "implausible" compared to the boost pressure and engine RPM.
ACTION: 1. Remove speed sensor; check for metal contact/rubbing on the sensor tip.
2. Check turbo shaft for "play" (wobble).
3. Inspect harness for interference from the alternator.
FIX: Replace Turbo Speed Sensor or replace Turbocharger if shaft play is excessive.
Red Seal field insights
A high-pitched whistle usually means the compressor wheel is slightly touching the housing. If the sensor tip is "shaved" or shiny, the turbo bearings are shot—do not just replace the sensor.
Same code keeps coming back?
That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.
Read before you touch anything
- This is general reference information, not a repair manual. It is for trained, qualified technicians.
- Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
- Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
- You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
- Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.
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