Fault code P0C31 – inverter “B” cooling system performance

Fault code P0C31 is called “Inverter “B” Cooling System Performance” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0C31

The P0C31 fault code is intended to be displayed only on hybrid vehicles. Indicates that the Powertrain Control Module (PCM) has detected a fault with the inverter cooling system. It refers to the inverter indicated by the letter “B”.

Fault code P0C31 – inverter

The inverter converts the high voltage direct current of the high voltage battery into alternating current for the electric motor. Also, the alternating current is used by the generator and other electric motors.

During the conversion process, an inverter, like any electrical device, generates heat, which can put it out of action if there is no cooling system. Therefore, like the electric motor and generator, the inverter is cooled by a special system including an electric pump, a fan and a radiator.

This cooling system is self-contained and independent of the engine cooling system. The Hybrid Control Module fully monitors the electric pump, fan and cooling system and records faults.

If the Hybrid Control Module detects a malfunction in the inverter cooling system’s electric pump, fan, or radiator, it will store a P0C31 code. The Malfunction Indicator Light (MIL) may then illuminate.

For most vehicles, it will take several failure cycles before the warning light comes on.

Symptoms of vehicle malfunctions

The main signal that an error P0C31 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. Other related fault codes may be present.
  3. Severe heating of the inverter.
  4. Reduced vehicle performance.
  5. Emergency engine shutdown due to inverter overheating.

The severity of fault code P0C31 is high, as there is a risk of excessive temperature rise when the inverter cooling system malfunctions. This, in turn, may cause the engine to shut down in an emergency.

Factors that can cause this error code

The error code P0C31 can mean that one or more of the following problems have occurred:

  • The cooling system of the inverter is defective.
  • The water-cooling pump (pump) is defective.
  • Corrosion, loose or broken electrical wiring.
  • Poor electrical connection of connectors.
  • The cooling system fan is defective.
  • Sometimes faulty hybrid module is the cause.

How to fix or reset OBD-2 code P0C31

Some suggested steps for troubleshooting and fix the error code P0C31:

  1. Connect an OBD-II scanner to the vehicle’s diagnostic connector and read all stored data and error codes.
  2. Clear the error codes from the computer memory and test-drive the vehicle to see if the P0C31 code appears again.
  3. If the error code appears again, visually inspect the electrical wires and connectors related to the inverter cooling system.
  4. If necessary, repair or replace any shorted, broken, damaged, or corroded components.
  5. Check the water-cooling system pump (pump).
  6. Test the cooling fan.
  7. Test the battery and make sure the system voltage is normal.
  8. If the problem persists, check and replace the hybrid control module if necessary.

Diagnose and repair of problems

The first step in the P0C31 troubleshooting process is to review the Technical Service Bulletins (TSB). For known problems with a particular vehicle.

The advanced diagnostic steps are very vehicle specific. They may require, special equipment and knowledge to accurately perform the steps.

Visual inspection

Perform a visual inspection of the inverter cooling system, check the coolant level. Inspect the hoses, they should not be pinched or clogged and there should be no cuts, tears or other damage.

If the system is checked and is in good condition, the cooling pump should be checked. Most often it is a failed pump that causes error P0C31.

Check the electrical connections of the inverter cooling system. Disconnect the wiring connectors and inspect for corrosion or bent contacts. If necessary, repair and apply dielectric grease to the terminals.

Also, check the operation of the cooling fan and for dirt and dust between the engine cooler, air conditioner, and inverter radiators. If the radiator cells are clogged, the fan will not be able to handle cooling efficiently.

If these steps could not help find the problem, there may be a bad connection to the hybrid system module or the module itself is defective. In this case, it is better to consult a specialist for reprogramming or replacing the control unit.

On which vehicles does this problem occur most frequently

Fault code P0C31 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Lexus
  • Mercedes-Benz
  • Toyota

Fault code P0C31 can sometimes be found with other errors. The most common are the following: P0A7A, P0A93, P0C32.

Video

Rate article
AutoNevod | Technical description of OBD-2 car faults and their solution
Add a comment