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Code P0481. Cooling Fan Relay 2 Control Circuit Malfunction

The code P0481 is a generic code related to a radiator fan malfunction. It is a failure that can greatly affect the engine, since it directly influences its cooling system.

Knowing how to locate this fault and act accordingly can prevent engine overheating and even more serious failures that can be catastrophic. Stay with us and let’s see more of this fault code and its solution.

Engine Cooling System Operation

As the vehicle runs, the radiator and engine are cooled by air of sufficient quality as it passes. When the vehicle is idling or stopped, there will be no air to pass through the radiator.

Therefore, a fan is necessary that activates at these key moments, when the temperature increases due to the low speed of the car. This ensures that the radiator always has enough air.

The PCM (powertrain control module) detects this increase in temperature through the coolant temperature sensor, located near the thermostat.

If the temperature reaches more than 100° C (The value depends on the make, model or engine of the vehicle), the PCM automatically commands the cooling fan relay to turn on its fan by supplying ground to the relay.

If there is any fault in the fan control electrical circuit, the motor will overheat, something you cannot afford to do.

Basically, the P0481 error code means that the cooling fan control circuit experienced a problem that caused it to malfunction.

The vehicle’s PCM controls the cooling fan, and the moment it determines that it is not working properly, it triggers the P0481 code and illuminates the Check Engine light.

Error code P0481 refers to the basic circuit and its related codes, error codes P0480, and error code P0482, which relate to failures of different speed relays.

You may also be interested in Code P0463. Causes, Symptoms and How to Fix It

What is Code P0481?

Code P0481 is defined as Cooling fan relay 2 control circuit malfunction. Refers to a failure of the cooling fan in the engine cooling system.

If this code is activated, the radiator cooling fan does not operate at one or more speeds. The specific problem relates to the average speed of the cooling fan.

When driving, enough air flows through the radiator to cool the engine effectively. When the vehicle stops, such as at a traffic light, air does not flow 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 (ECT).

When the temperature reaches approximately 100°C, 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 invalid, the P0481 code is set. If there is a problem in the circuit that causes the fan to not work, it can cause the motor to overheat.

Symptoms of Code P0481

When this P0481 code is activated, some of the following symptoms may occur:

  • The malfunction light on the dashboard activates.
  • The engine temperature increases.
  • The engine temperature becomes unstable.
  • On some models, the engine shuts off automatically as a safety measure.

The severity of the P0481 fault code is high, as there is a risk of the car’s engine overheating, which can lead to its damage or complete failure.

We do not recommend that you drive the car in these conditions. You should take it in for repairs immediately.

Causes of Code P0481

Error code P0481 It may mean that the car is experiencing the following faults that affect the radiator fan:

  • The fan control relay with problems.
  • Wiring problem or damaged fan connector.
  • Defective or damaged cooling fan.
  • Coolant temperature (ECT) sensor problem.
  • Low system voltage.
  • Damaged or deteriorated system wiring harness.
  • Poor electrical connections in the cooling fan circuit.
  • Faulty coolant temperature sensor.

How to Diagnose Code P0481

Some suggested steps to troubleshoot and fix error code P0481:

1. Scan your car

Connect the OBD2 scanner to your car and check the error code with its related data. The P0481 code may appear alone or may be accompanied by another code depending on the characteristics of the fault.

Clear the error codes from the computer’s memory and test drive the vehicle to see if the P0481 code appears again.

If the error code appears again, visually inspect the electrical cables and connectors related to the fan control system.

2. Locate the main fan

Many vehicles will have two fans, one to cool the engine, and the second to cool the air conditioning condenser. When this failure occurs, it refers to the main fan, that of the cooling system.

To find out the location of the main fan, just look at which one is actually mounted on top of the radiator. The other will be above the air conditioning exchanger.

Additionally, many cars have multi-speed fans. They can have up to three fan speed relays: low, medium, and high.

3. Inspect the main fan

Look at the main fan and make sure there are no obstructions blocking the airflow in front of the radiator. Manually spin the fan; if it does not spin, there is most likely a problem with the bearings, and they need to be replaced.

Check the electrical connection of the fan. Disconnect the connector and inspect it for corrosion or bent contacts.

4. Check the system fuses and relays

Open the fuse box and inspect the cooling fan relay fuses. If they are OK, remove the cooling fan relay and test it. You can usually see the location and identification of the relay on the same cover.

Use an ohmmeter to check the continuity between the fan side relay terminal and the fan connector. If there is a signal, then the fan is defective.

Otherwise, the harness between the fuse box and the fan is damaged.

5. Check the status of the wiring

Check that there is no damage of any kind to the fan and ECT sensor wiring. In the event of damage, you must proceed to change the wiring.

6. Inspect the ECT sensor

Check the coolant temperature (ECT) sensor with an ohmmeter. Remove the connector, let the motor cool, and set the ohmmeter. Check the sensor terminals.

If the ECT is defective, you must replace it as it cannot be repaired.

7. Check the battery voltage

Test the battery and make sure the system voltage is normal. If the battery cannot deliver its rated voltage, which is usually above 12 volts, you should recharge or replace it.

If these steps fail to find the fault, there may be a poor connection to the PCM or the PCM itself may be faulty. If this is the case, it is best to consult a technician to reprogram or replace the computer.

How to Fix Code P0481

Due to this P0481 error code, you may not face any driving problems, but if this code is ignored, it can lead to serious problems.

In the event that the cooling system is not functioning properly, your vehicle’s engine will begin to experience excess heat and can cause serious damage to crucial components, leading to costly repairs.

Sometimes small electrical problems or malfunctions can trigger false codes, and simple things like a faulty cable or corrosion around connectors can cause trouble codes to appear.

Component replacements

Repairs for this error code are quite simple and straightforward, which can of course be derived from a thorough diagnosis. Some of the common repairs are:

Cooling fan relay: A cooling fan relay is used on vehicles that have an electric fan to cool the engine.

The fan relay receives the signal and activates it to supply the power the fan needs to operate. Please make sure this relay works properly to avoid serious problems.

Cooling fan: A radiator cooling fan is a mechanical or electrical fan that helps push or pull air through the radiator.

If it doesn’t work well, it can cause major problems such as overheating, which can further damage your car’s major components.

Coolant temperature sensor: A coolant temperature (ECT) sensor is used to measure the temperature of the coolant/antifreeze mixture in the cooling system, giving an indication of how much heat the engine is emitting.

It is also one of the crucial components, to ensure its efficient functionality to avoid associated trouble codes.

Coolant pressure sensor: The refrigerant pressure switch controls the pressure in the air conditioning system to ensure it is working properly.

Replace it immediately if found defective.

Common Errors When Detecting Code P0481

The most common mistake people make when dealing with this error code is skipping diagnostic steps. It is crucial to identify which component is causing the problem, before deciding to make substitutions.

Many people have replaced the cooling fan believing that that was the fault, either the control relay or a fuse. Doing the diagnosis well will give us the necessary information to repair or replace efficiently.

This code should be rectified as soon as possible, as engine overheating can damage a number of crucial components and lead to very expensive repairs.

Is Code P0481 Serious?

Very serious. The code indicates a failure in one of the components of the engine cooling system. You cannot drive the car if you have a faulty cooling fan.

If the engine overheats, much more serious failures can occur, such as deformation of the cylinder head, damage to the main gaskets, or perforation of the block. They are very costly failures and put the life of your engine at risk.


You may also be interested in Code P0480. Symptoms, Causes, Diagnosis and Solution

A P0481 code is one of those faults where you must act quickly if you don’t want things to get out of control.

Although you will not have driving problems with this code activated, you cannot continue driving in these conditions since the cooling fan is not working.

Engine overheating is not a game, it is one of the worst faults that your car can suffer and you should avoid it at all costs. It diagnoses and repairs the fault which is usually easy to detect and cheap to repair.

This way you don’t put your engine at risk.

If you want to know other articles similar to Code P0481. For Cooling Fan Relay 2 Control Circuit Malfunction you can visit the category Fault Codes.


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