Diagnostic Overview
CAT fault code 102-18 indicates intake manifold pressure or boost pressure below normal at a moderate severity level. This usually means the engine is not building enough boost for the current load, or the ECM believes boost is too low. It can cause low power, smoke, poor acceleration, high exhaust temperature, or derate.
Likely Causes
Charge-air cooler leak; split boot; exhaust leak before turbo; restricted intake; sticking turbo control; faulty boost sensor; worn turbocharger; EGR issue affecting air flow.
What To Check First
Pressure-test the charge-air system, inspect turbo and exhaust plumbing, verify boost sensor accuracy, and check turbo control response during a loaded test.