Diagnostic Overview
CAT fault code 2629-04 generally points to a turbocharger or air-system pressure sensor circuit voltage below normal. FMI 4 often indicates a short to ground, failed sensor, or wiring issue. The ECM may use this signal for turbocharger control and engine protection, so an invalid reading can create low-power or derate complaints.
Likely Causes
Short to ground; failed pressure sensor; damaged harness; poor connector contact; low reference voltage; moisture in connector.
What To Check First
Confirm the full Cat ET description, inspect wiring and connectors, test signal voltage, and compare sensor data to known-good pressure conditions.
