Fault Family System: Powertrain (P-Codes) 29 SAE Codes

DC-DC Converter Temperature

Diagnostic & Technical Explanation

Code P0C38 sets when the control module detects an implausible reading from the sensor monitoring the DC/DC converter's switching-transistor heatsink — the reading disagrees with the converter's commanded 12V output current draw, the dominant source of its internal switching-loss heating. The converter is typically buried in a sealed enclosure with its own small coolant loop or fan, so common causes are a clogged or air-locked converter cooling passage, a cooling fan that has failed or is caked with debris, and a sensor lead that corroded inside the sealed housing. Because 12V accessory load (not HV bus load) drives this component's heat output, a high-accessory-draw condition such as a stuck-on blower can produce a genuine high reading the sensor is correctly reporting.

These 29 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 29 times.

Codes in this family (29)

Code	Definition	Repair coverage
P0C38	DC/DC Converter Temperature Sensor A Circuit	4 ranked fixes
P0C39	DC/DC Converter Temperature Sensor A Range/Performance	4 ranked fixes
P0C3A	DC/DC Converter Temperature Sensor A Low	4 ranked fixes
P0C3B	DC/DC Converter Temperature Sensor A High	4 ranked fixes
P0C3C	DC/DC Converter Temperature Sensor A Intermittent/Erratic	4 ranked fixes
P0C3D	DC/DC Converter Temperature Sensor B Circuit	4 ranked fixes
P0C3E	DC/DC Converter Temperature Sensor B Range/Performance	4 ranked fixes
P0C3F	DC/DC Converter Temperature Sensor B Low	4 ranked fixes
P0C40	DC/DC Converter Temperature Sensor B High	4 ranked fixes
P0C41	DC/DC Converter Temperature Sensor B Intermittent/Erratic	4 ranked fixes
P0D32	DC/DC Converter A Over Temperature	4 ranked fixes
P0E58	DC/DC Converter Temperature Sensor C Circuit	4 ranked fixes
P0E59	DC/DC Converter Temperature Sensor C Circuit Range/Performance	4 ranked fixes
P0E5A	DC/DC Converter Temperature Sensor C Circuit Low	4 ranked fixes
P0E5B	DC/DC Converter Temperature Sensor C Circuit High	4 ranked fixes
P0E5C	DC/DC Converter Temperature Sensor C Circuit Intermittent/Erratic	4 ranked fixes
P0EA6	DC/DC Converter B Over Temperature	4 ranked fixes
P2C8C	DC/DC Converter Temperature Sensor D Circuit	4 ranked fixes
P2C8D	DC/DC Converter Temperature Sensor D Circuit Range/Performance	4 ranked fixes
P2C8E	DC/DC Converter Temperature Sensor D Circuit Low	4 ranked fixes
P2C8F	DC/DC Converter Temperature Sensor D Circuit High	4 ranked fixes
P2CA5	DC/DC Converter Temperature Sensor E Circuit	4 ranked fixes
P2CA6	DC/DC Converter Temperature Sensor E Circuit Low	4 ranked fixes
P2CA7	DC/DC Converter Temperature Sensor E Circuit High	4 ranked fixes
P2CA8	DC/DC Converter Temperature Sensor E Circuit Range/Performance	4 ranked fixes
P2CA9	DC/DC Converter Temperature Sensor F Circuit	4 ranked fixes
P2CAA	DC/DC Converter Temperature Sensor F Circuit Low	4 ranked fixes
P2CAB	DC/DC Converter Temperature Sensor F Circuit High	4 ranked fixes
P2CAC	DC/DC Converter Temperature Sensor F Circuit Range/Performance	4 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

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