P2CAC

Code

Generic P — Powertrain

DC/DC Converter Temperature Sensor F Circuit Range/Performance

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 34 RU: 27

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Page language: EN

Causes

Open or short in sensor wiring (power, signal, or ground)
Corroded, loose, or damaged connector at the sensor or control module
Failed or out-of-spec temperature sensor (thermistor)
Poor ground or intermittent connection
Water intrusion or contamination of connector
Internal DC/DC converter fault affecting the sensor

Symptoms

Check Engine / MIL or dedicated hybrid/electric warning lamp illuminated
Stored P2CAC with possible related codes
Reduced DC/DC converter performance or limp-home/reduced accessory function
12 V accessory faults or intermittent accessory power loss (on hybrid/EV systems)
Possible erroneous temperature readings in scan-tool live data

What to check

Read and record all stored codes and freeze-frame data with a capable scan tool
Check for related codes (other DC/DC converter or temperature sensor circuit codes)
Visual inspection of sensor, connector, and wiring for damage, corrosion, heat damage, or water entry
Backprobe sensor connector and observe live data while key ON/engine off and while system operating (if safe)
Measure reference voltage and ground at the sensor connector
Measure sensor resistance at ambient temperature and compare to specification (service manual)

Signal parameters

Sensor type: typically an NTC thermistor (resistance varies with temperature)
Reference voltage to sensor: commonly 5 V (may vary by manufacturer) — check service manual
Typical signal voltage range: approximately 0.1–4.9 V (depends on actual temp and vehicle design)
Typical resistance at 25°C: manufacturer-specific (commonly in the 1 kΩ to 100 kΩ family for many thermistors) — consult service specification
Operating temperature monitoring range often spans roughly -40°C to +150°C depending on sensor

Diagnostic algorithm

With a scan tool, record the code P2CAC, freeze-frame data and any related codes. Clear codes and attempt to reproduce.
Perform a visual inspection of the DC/DC converter area: look for damaged wiring, chafed insulation, heat damage, coolant/water contamination, and poor/loose connectors.
Backprobe the temperature sensor connector. With key ON (or system energized per service manual), verify the reference voltage and ground presence at the connector.
Measure the sensor signal voltage with the sensor in ambient conditions and compare to expected values. If possible, heat or cool the sensor slightly (hair dryer or ice pack) and verify the signal changes smoothly and correspondingly.
With the sensor disconnected, measure sensor resistance across its terminals and compare to the manufacturer's resistance vs. temperature table. Replace sensor if resistance is out of spec.
Inspect and test continuity of circuit wires between sensor and control module. Check for short to voltage, short to ground, or open circuit. Repair any damaged wiring or connectors.
Perform a wiggle test of the harness and connectors while monitoring live data for intermittent faults. Repair any intermittent connections.
If wiring and sensor check good, verify the control module input circuit and reference voltage. If reference voltage is missing or incorrect, diagnose/repair module power/ground or module itself per service procedures.
After repairs, clear codes, perform a full system test and verify the code does not return under normal operating conditions.

Likely causes

Damaged or corroded connector/wiring between sensor and control module (most common)
Failed temperature sensor (thermistor) at the DC/DC converter
Intermittent connection or poor ground at the sensor
Module reference voltage or input circuit fault (less common)