P0480 - OBD Trouble Code

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Diagnostic Trouble Code P0480 is defined as Cooling Fan 1 Control Circuit Malfunction. It indicates that PCM has detected an incorrect amount of voltage (high or low) in the electric cooling fan control circuit. Voltage variations that vary by greater than 10-percent of the manufacturer’s specified reference voltage will cause this code to be stored and this code can become serious if the vehicle is allowed to overheat which can ultimately lead to the engine damage. If you discover this code, then stop driving the vehicle till the code is rectified.

OBD-II Code P0480 is technically described as a Cooling Fan Relay 1 Control Circuit. It is a generic code applying to all OBD II (on board diagnostics) vehicles. While driving a vehicle an adequate amount of air goes through the radiator, which viably cools the engine but when we stop the vehicle or when it is in idle mode then no air is passing through the radiator and the engine begins to increase in temperature. The PCM recognize the raise in engine temperature with the help of coolant temperature sensor positioned near the thermostat. When the temperature reaches about 223-degrees F, the PCM will command the cooling fan relay to turn on the fan. When the PCM try to activate the fan and discover the command and the result do not match, the code is set. The PCM then triggers a Check Engine Light to illuminate on the dashboard.

What causes this problem with the Cooling Fan I Control Circuit Malfunction?

• Defective cooling fan 1
• Fan control relay failure
• Damaged coolant temperature sensor
• Fan circuit has bad electrical connection
• Frayed AC selector switch
• Inoperative vehicle speed sensor

1. Refrigerant Pressure Sensor - The refrigerant pressure sensor, or switch, is designed to protect the A/C system against incorrect refrigerant pressure. It should work properly; replace it if you discover it faulty.
2. Cooling Fan - A radiator cooling fan is device that can help regulate engine temperature by pulling air through a radiator. Make sure its efficient functionality to avoid all the related codes.
3. Cooling Fan Harness - Defective, corroded or broken wiring harness could also be a reason for creating this code. So, make sure it should be perfect else can create problems.
4. Intake Air Temperature Sensor - The Intake Air Temperature sensor (IAT) monitors the temperature of the air entering the engine. The engine computer (PCM) needs this information to estimate air density so it can balance air air/fuel mixture. If you find it faulty then replace it immediately.
5. A/C Selector Switch - Always replace the inoperative or damaged AC selector switch to avoid all the associated trouble codes.
6. Vehicle Speed Sensor - A vehicle speed sensor generates a magnetic pulse in the form of a wave proportional to the speed of the vehicle. The power control module (also known as the electrical control module) uses the VSS frequency signal to manipulate multiple electrical subsystems in a vehicle, such as fuel injection, ignition, cruise control operation, torque, and clutch lock-up. Frayed VSS always create problems, so replace them if discover faulty.

Due to inoperative fan you may only feel the overheated vehicle and in some cases, there may be performance problems as well. Some other common symptoms include:

• Raised engine temperature
• Knocking while acceleration
• Reduced fuel economy
• Misfiring while stopping the vehicle
• Illuminated check engine light

If you detect error code P0480 and the fans are not operating then the vehicle should not be driven as it may cause overheating which ultimately leads to engine damage or the engine to fail entirely. Repairs for this error code are not difficult and following repairs and replacements can actually help you to fix this code:

• Repair or replace the faulty cooling fan 1
• Replace the frayed vehicle speed sensor
• Replace the inoperative AC pressure switch
• Repair the faulty electrical connections
• Repair or replace the defective fan wiring harness
• Replace the engine coolant temperature sensor
• Replace the faulty fan control relay

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Many vehicles will have two engine fans, one for engine cooling and the second for cooling the air conditioning condenser, and additional cooling for the engine. The fan that is not in front of the air conditioning condenser is the main cooling fan and the one to concentrate on initially. Additionally, many vehicles have multi-speed fans requiring as many as three fan speed relays for low, medium and high. So, diagnose carefully and we recommend you to follow technical service bulletins for the help. Steps to diagnose this error code are as follows:

• Begin with visual inspection and look at the fan to make sure there is no obstruction in front of the radiator blocking airflow.
• Inspect the electrical connection at the fan. Pull the connector apart and look for corrosion or bent pins. Repair if necessary.
• Open the fuse block and inspect the cooling fan relay fuses.
• Look at the circuit diagram displayed for the simple open and shut circuit.
• Verify the battery positive terminal in the relay block with constant power and use a test light to find the hot terminal.
• Jump the battery terminal to the fan harness terminal and the fan will operate.
• If not, disconnect the fan connection at the fan and using an ohmmeter check the continuity between the fan side of the relay terminal and the connector at the fan.
• Check all the relays in the same fashion to be sure they are all working.
• Jump the battery plus terminal in the first test with this switched terminal and place an additional jumper from the negative terminal on the relay to ground.
• If the circuit has not closed or the relay has not clicked, the relay is bad.
• If there was no switched power at the relay, the ignition switch is suspect.
• Check the CTS with an ohmmeter and probe the sensor terminals.
• Shut the engine down and pull the CTS plug again. Check it with the ohmmeter, there should be a big change in resistance, if not the sensor is bad.
• If the above procedure could not find a failure, the probability is that a poor connection to the PCM or the PCM itself is at fault.

Common Mistakes When Diagnosing the P0480 Code

Technicians report the replacement of cooling fan motors without performing a thorough diagnosis results in many unsuccessful repairs. Cooling fan relays have been the subject of several technical service bulletins and recall campaigns in late model vehicles.