Universal HD Fault Code
Free · no signupSPN 108 FMI 03
Sluggish High Altitude Power / Rich Burn
System
Sensors / Ambient
Symptom
Sluggish High Altitude Power / Rich Burn
Diagnosis & fix steps
LOGIC: Barometric Pressure Sensor Circuit Voltage High / Open.
ACTION: Measure reference and signal voltages at the atmospheric/barometric pressure sensor (often built directly into the engine ECM or mounted on the engine block). Verify 5V supply and chassis ground integrity; test signal pin continuity.
Red Seal field insights
Altitude Compensation: The ECM uses barometric pressure to calculate air density for altitude derating and turbocharger wastegate/VGT positioning. An open circuit locks the ECM into a default sea-level air model, causing smoking at elevation.
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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