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.
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