SPN 102 FMI 18
CAUTION
Boost pressure
Intake manifold pressure is low: the truck is down on power.
SPN 102 FMI 18: Intake manifold pressure is low: the truck is down on power. Caution: you can keep driving carefully, but the engine may derate; get it addressed soon.
Mechanical · Air intake / Turbo
What it means
Boost pressure fell below the expected value for that load and rpm. It is usually a charge-air leak, a sooted-up variable geometry actuator, or a leaking charge air cooler long before it is a failed turbo.
Most likely causes
Charge-air pipe leak or loose clamp
Very likely
VGT actuator stuck with soot
Very likely
Leaking or plugged charge air cooler
Likely
Intake pressure sensor reading low
Likely
Tests, cheapest and most decisive first
1. Pressurize the charge-air system to 25 psi
Expected result: Less than 5 psi drop in one minute
Tool: Pressure test kit
2. Command the VGT actuator with the scanner and watch travel
Expected result: Full, smooth 0 to 100% travel
Tool: J1939 scanner
3. Compare intake pressure with barometric pressure, engine off
Expected result: Both equal within 1 kPa
Tool: J1939 scanner
Read it off your own dash
Take one photo and DERATE tells you whether you can keep driving.
DERATEDERATE assists. It does not replace inspection by a qualified technician.