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ECM Performance — Diesel ECM Programming
TurboCaterpillar Diesel ECM

SPN 2629 FMI 4

Turbocharger boost control and air-handling faults.

System
Caterpillar Turbo

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.

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Related Turbo Fault Codes

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