C1B14

Code

Generic C — Chassis

DC-DC Converter Overtemperature

Brand: Generic

Type: C — Chassis

Views: UK: 11 EN: 10 RU: 9

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Blocked or restricted converter cooling (air or liquid)
Failed cooling fan, pump, or coolant circulation
Low or contaminated coolant (if liquid‑cooled)
Faulty temperature sensor or sensor circuit (open/short/erratic)
Excessive DC‑DC electrical load or high input voltage
Internal component failure in the DC‑DC converter (IGBTs, capacitors, etc.)

Symptoms

DTC C1B14 (DC‑DC Converter Overtemperature) stored
12V battery not charging or reduced 12V system voltage
HV/charge warning lamp, MIL, or instrument cluster message
Reduced vehicle functions or limp mode initiated
Unusual odors (hot/electrical) or visible heat damage at module
Cooling fan or pump running continuously or at high speed

What to check

Record freeze‑frame and full history of the fault with a scan tool
Visually inspect DC‑DC module area for debris, corrosion, melted wiring, or heat damage
Check cooling airflow path, fan operation, and fan shrouds for obstruction
If liquid cooled: inspect coolant level, hoses, fittings, and for leaks
Read live data: converter temperature, coolant temp, DC‑DC input voltage, output voltage and current, fan/pump command/status
Measure temperature sensor resistance/voltage at connector and compare to specification

Signal parameters

DC‑DC module internal temperature (°C) — live value and trip threshold
Temperature sensor voltage (0–5 V) or resistance (Ω) vs. specified curve
DC‑DC input (HV) voltage (V)
DC‑DC output (12V system) voltage (nominal ~13.5–14.8 V when charging)
DC‑DC output current (A) / load current
Cooling fan command and actual RPM or status

Diagnostic algorithm

Observe safety: follow HV isolation, PPE, and manufacturer procedures before any work on the high‑voltage system.
Using a scan tool, read and record DTCs, freeze‑frame data and live parameters (module temp, input/output voltages, fan/pump status).
Perform a visual inspection for heat damage, melted insulation, burnt connectors, debris on cooling fins, or blocked airflow.
Verify cooling components: command fan(s) and pump(s) via the scan tool and confirm operation (electrical and mechanical).
If liquid cooled, check coolant level and condition; pressure test the cooling circuit if a leak is suspected.
Probe the temperature sensor circuit at the module connector: inspect pins, measure sensor voltage or resistance at ambient and while warming (compare to spec).
With the vehicle safely powered and under controlled load, monitor converter temperature rise vs. load. Verify whether temperature rises abnormally under normal load.
Measure DC‑DC output voltage and current under load to confirm the module is derating or failing to regulate.
Inspect wiring and high‑current connections for high resistance or signs of overheating; repair any damaged connectors or wiring.
If sensors, cooling and external circuitry check good but overtemperature persists, suspect internal converter fault — follow manufacturer procedure for module replacement.
After repair or replacement, clear DTCs and perform a full drive/charge cycle while monitoring temperatures and operation to confirm the fault does not return.

Likely causes

Bad or disconnected DC‑DC temperature sensor
Cooling fan or pump failure or airflow blockage
Low coolant level or clogged coolant passages (if applicable)
High DC‑DC load or repeated high‑current events causing overheating
Internal converter failure requiring module replacement

Fault status

⚠️ Status

DC‑DC Converter Overtemperature — module temperature exceeded safe operating threshold; output may be reduced or shut down until condition is resolved.

🔴 Repair difficulty: Hard

⏱️ Diagnostic time: 1.0 - 3.0 hours