Low or degraded coolant in the inverter cooling loop, leading to inadequate heat removal from the phase U modules.; A failing coolant pump or restricted coolant passage that reduces flow specifically to the inverter assembly.; High resistance or loose connection at the phase U cable between the inverter and motor B, causing excess heat generation.; Internal degradation of the phase U power switching devices (insulated-gate bipolar transistors or metal-oxide-semiconductor field-effect transistors) increasing conduction losses.; A faulty temperature sensor on the phase U module reporting falsely high values to the inverter controller.; Software or calibration issues in the inverter control module that misjudge thermal thresholds under certain operating conditions.; Extreme sustained load or repeated hard acceleration that pushes the inverter beyond its designed thermal capacity.

DTC codes / P0Cxx · Hybrid propulsion / P0C14

P0C14Drive Motor B Inverter Phase U Over Temperature

Q: What does code P0C14 mean?

Drive Motor B Inverter Phase U Over Temperature. P0C14 indicates that the inverter responsible for driving electric motor B has detected an over-temperature condition on phase U of its output. The inverter control module continuously monitors the temperature of the phase U switching devices and reports this code when that temperature exceeds a calibrated threshold, typically due to excessive current, poor cooling, or a failing component.

P0C14 indicates that the inverter responsible for driving electric motor B has detected an over-temperature condition on phase U of its output. The inverter control module continuously monitors the temperature of the phase U switching devices and reports this code when that temperature exceeds a calibrated threshold, typically due to excessive current, poor cooling, or a failing component.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light or service vehicle soon message, often with no other noticeable symptoms.
Reduced power or limp-home mode as the inverter limits current to protect the phase U hardware.
Intermittent loss of drive motor B operation, especially under high load or during sustained driving.
Audible cooling fan running excessively or continuously as the system tries to manage inverter temperature.
Overheating warning message on the dashboard in vehicles equipped with a dedicated EV thermal display.

Common causes, most likely first

Low or degraded coolant in the inverter cooling loop, leading to inadequate heat removal from the phase U modules.
A failing coolant pump or restricted coolant passage that reduces flow specifically to the inverter assembly.
High resistance or loose connection at the phase U cable between the inverter and motor B, causing excess heat generation.
Internal degradation of the phase U power switching devices (insulated-gate bipolar transistors or metal-oxide-semiconductor field-effect transistors) increasing conduction losses.
A faulty temperature sensor on the phase U module reporting falsely high values to the inverter controller.
Software or calibration issues in the inverter control module that misjudge thermal thresholds under certain operating conditions.
Extreme sustained load or repeated hard acceleration that pushes the inverter beyond its designed thermal capacity.

How to diagnose and fix it

Verify coolant level and condition in the inverter cooling system, and pressure-test the loop for leaks or blockages.
Check coolant pump operation and confirm adequate flow through the inverter using a scan tool to command the pump and observe temperature response.
Inspect the phase U cable and connectors for tightness, corrosion, or heat damage, and measure resistance end-to-end if accessible.
Use a scan tool to read live inverter temperature data and compare the phase U sensor reading with other phases to identify a faulty sensor.
Perform a thorough visual inspection of the inverter assembly for signs of overheating, such as discoloration or melted components, and check for updated software or service bulletins.
If all external factors are ruled out, replace the inverter assembly or the specific phase U power module as directed by the manufacturer's service procedure.
After repair, clear the code and perform a road test under varying loads to confirm the over-temperature condition does not return.

Cooling system faults often masquerade as inverter failure

A significant number of P0C14 cases are resolved by repairing the inverter cooling circuit rather than replacing the inverter itself, so always verify coolant flow and pump operation first.
The phase U temperature sensor can drift and report false over-temperature values without any actual overheating, which is why comparing live data across phases is a critical diagnostic step.
Loose or corroded connections at the phase U terminals create localized resistance that generates heat only under load, so a visual inspection at rest may miss the problem.
Some vehicles set P0C14 as a history code after a single extreme driving event, and it may not indicate a persistent fault if the cooling system is otherwise healthy.
The inverter may derate power output before setting the code, so drivers sometimes notice reduced performance without a warning light until the condition worsens.

Can I keep driving with P0C14?

Do not continue driving under heavy load or at high speeds, as the over-temperature condition can lead to inverter failure and a sudden loss of propulsion. Limit driving to a slow, gentle trip directly to a qualified service facility, and avoid any situation that demands maximum power.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.