Fault code P0482 – cooling fan relay 3 control circuit malfunction

Fault code P0482 is called “Cooling Fan Relay 3 Control Circuit Malfunction” 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 P0482

Error P0482 refers to a fault in the cooling fan control relay 3 circuit. If this code is activated, the radiator cooling fan will not operate at one or more speeds. The specific problem relates to the high speed of the cooling fan.

Fault code P0482 – cooling fan relay 3 control circuit malfunction

When driving, enough air flows through the radiator to effectively cool the engine. When the vehicle is stopped, such as at a stoplight, air is not flowing through the radiator and the engine begins to heat up.

The transmission control module (PCM) detects an increase in engine temperature, through the coolant temperature sensor (CTS). This sensor is located near the thermostat.

When the temperature reaches approximately 223°F, the PCM commands the cooling fan relay to turn on.

The PCM attempts to activate the fan, and if it finds that the command is not valid, code P0482 is set. If there is a problem in the circuit that causes the fan not to run, it may cause the engine to overheat.

Symptoms of vehicle malfunctions

The main signal that an error P0482 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. Check engine control lamp on the control panel will light up (the code will be recorded in the memory as a malfunction).
  2. Engine temperature rises in traffic or when idling.
  3. Unstable engine operating temperature.
  4. Cooling fan does not work.

The severity of fault code P0482 is high, since there is a risk of overheating the vehicle engine, which may cause damage or complete failure of the engine.

Factors that can cause this error code

The error code P0482 can mean that one or more of the following problems have occurred:

  • Fan control relay 3 is defective.
  • Wiring problem or damaged connector.
  • Corrosion of electrical wires or connections.
  • Defective cooling fan.
  • Coolant temperature sensor (CTS) problem.
  • Low system voltage.
  • Sometimes faulty PCM is the cause.

How to fix or reset OBD-2 code P0482

Some suggested steps for troubleshooting and fix the error code P0482:

  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 code P0482 appears again.
  3. If the error code appears again, visually inspect the electrical wires and connectors related to the fan control system.
  4. If necessary, repair or replace any shorted, cut, damaged or corroded components.
  5. Test fan operation.
  6. Check engine coolant temperature sensor operation.
  7. Check the fan control relay and replace it if necessary.
  8. Test the battery and make sure the system voltage is normal.
  9. If the problem persists, check and replace the engine control module (PCM) if necessary.

Diagnose and repair of problems

The first step in the P0482 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. It may require, special equipment and knowledge to accurately perform the steps.

Many vehicles will have two fans, one used to cool the engine. And the second is for cooling the air conditioner condenser and additional engine cooling.

The fan that is not in front of the air conditioner condenser is the main cooling fan and should be focused on initially. Also, many cars have multi-speed fans. They can have up to three fan speed relays: low, medium and high.

Visual inspection

Open the hood and do a visual inspection. Look at the fan and make sure there are no obstructions blocking air flow in front of the radiator. Manually spin the fan, if it does not spin, there is most likely a problem with the bearings, they should be replaced.

Check the electrical connection of the fan. Disconnect the connector and inspect it for corrosion or bent contacts. Repair if necessary and apply dielectric grease to terminals.

Open the fuse box and inspect the cooling fan relay fuses. If they are OK, remove the cooling fan relay and test it. The bottom of the fuse box cover usually indicates the location.

Use an ohmmeter to check for continuity between the relay terminal on the fan side and the connector on the fan. If there is a signal, then the fan is defective. Otherwise, the harness between the fuse box and the fan is faulty.

Check the coolant temperature sensor (CTS) with an ohmmeter. Remove the connector, allow the engine to cool, and set the ohmmeter to the 200000 scale. Also check the sensor terminals.

If these steps failed to find the failure, there may be a bad connection to the PCM or the PCM itself is faulty. If this is the case, it is best to consult a technician for reprogramming or replacing the ECU.

On which vehicles does this problem occur most frequently

Fault code P0482 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Cadillac (DeVille)
  • Dodge (RAM)
  • Fiat (Ducato)
  • Mazda
  • Opel (Astra, Corsa, Zafira)
  • Peugeot (Boxer)

Fault code P0482 can sometimes be found with other errors. The most common are the following: P0480, P0481, P0483, P0484, P0485.


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