Diagnostic Overview
CAT fault code 2738-03 is typically related to a turbocharger, intake, or air-management sensor circuit voltage above normal. The exact sensor should be verified in Cat ET. Because FMI 3 points to high voltage, the fault is usually in the sensor circuit rather than a confirmed mechanical turbo failure. Incorrect air-system data can cause improper boost control, low power, or derate.
Likely Causes
Short to voltage; failed air/turbo sensor; open ground; damaged harness; connector corrosion; water intrusion; incorrect sensor installed.
What To Check First
Use Cat ET to identify the sensor, check 5-volt reference and ground, inspect the connector, and compare key-on readings to expected atmospheric values.