Diagnostic Overview
CAT fault code 102-15 usually indicates intake manifold pressure or boost pressure above normal at a least-severe level. The ECM is warning that boost is higher than expected but may not yet be at the most severe threshold. This can be early evidence of turbo control problems, sensor drift, or operating conditions that are pushing boost out of range.
Likely Causes
Mild overboost; sticking VGT/wastegate; incorrect boost sensor reading; plugged sensor port; exhaust restriction; calibration or load condition issue.
What To Check First
Compare boost data to specifications, inspect turbo control movement, check sensor accuracy, and look for related exhaust restriction or turbo actuator codes.