What does it mean?
This generic powertrain/engine diagnostic code generally applies to all OBDII-equipped engines but appears more frequently in certain Ford, Isuzu, Mazda, Mercedes Benz, and Subaru vehicles.
The cooling fan module is typically mounted behind the radiator in front of the engine. The cooling fan module is usually controlled by the Powertrain Control Module (PCM) based on the inputs wired to it.
The PCM receives these inputs via voltage signals to determine the engine coolant and intake air temperatures, air conditioning pressures, and vehicle speed. This code is set if these inputs do not match the normal operating voltages stored in the PCM’s memory, or if the cooling fan operation does not match the predetermined information stored in the PCM.
P0483 might have been set due to mechanical temperature issues (incorrect coolant temperature due to a stuck thermostat/faulty water pump); or electrical issues (cooling fan circuit failure). These cannot be overlooked during the troubleshooting phase, especially when dealing with an intermittent problem. Troubleshooting steps may vary by manufacturer, cooling fan module type, and wire colors.
Related cooling fan fault codes include:
P0480 Cooling Fan Control Circuit 1 Malfunction
P0481 Cooling Fan Control Circuit 2 Malfunction
P0482 Cooling Fan Control Circuit 3 Malfunction
P0484 Cooling Fan Circuit High Current
P0485 Cooling Fan Power/Ground Circuit Malfunction
Severity and Symptoms
The severity depends on the failure. In case of mechanical failure; severe. In case of electrical failure, it may not be as severe as the PCM can compensate as long as the engine does not overheat. While the PCM compensates, the temperature gauge should be monitored during all driving cycles. Typically, the fans run all the time (100% duty cycle).
Symptoms of a P0483 fault code may include:
Malfunction indicator light illuminated
Engine overheating
Air conditioning system not functioning properly
Potential Causes
Typically, the causes for this code to set are as follows:
Open in the power circuit between the cooling fan module and the PCM – possible
Short to ground in the cooling fan module power circuit – possible
Cooling system malfunction – faulty thermostat/water pump – very likely
Faulty cooling fan module – possible
Faulty PCM – highly unlikely
Diagnostic and Repair Procedures
A good starting point is always to search for a Technical Service Bulletin (TSB) for your specific vehicle. The vehicle manufacturer may have a PCM flash/reprogramming to address this issue, and it is worth checking before discovering you have taken a long/wrong path.
Next, locate the cooling fan module on your specific vehicle. The cooling fan module (cooling fans) is typically mounted behind the radiator in front of the engine. Once located, visually inspect the connectors and wiring. Look for scratches, rubbing, bare wires, burns, or melted plastic. Separate the connectors and carefully inspect the terminals (the metal parts) inside the connectors. See if they appear burned or have a greenish tint indicating corrosion. Use electrical contact cleaner and a plastic bristle brush if terminal cleaning is necessary. Let it dry and apply electrical grease where the terminals make contact.
If you have a scan tool, clear the diagnostic codes from memory and see if P0483 returns. If not, the connections were likely your problem.
If the code returns, check the integrity of the cooling system. Ensure the thermostat and water pump are functioning correctly. Once the engine has cooled, remove the radiator cap and ensure it seals properly on the radiator. If you have doubts about these cooling system components, replace them first, as this is the most common area of concern related to this fault code. Once done, clear the codes and test the vehicle to ensure P0483 does not return.
If the code returns, we will need to test the fans and their associated circuits. Typically, there are 2 wires to each cooling fan module. First, disconnect the wiring harness going to the cooling fan module. With a digital volt ohm meter (DVOM), connect one meter lead to one terminal of one of the fans. Connect the remaining meter lead to the other terminal of the fan. It should not be open or shorted. Check the resistance specifications for your specific vehicle. If the fan motor is open or shorted (infinite resistance or no resistance/0 ohms), replace the cooling fan module or, if available, the cooling fan motor.
If this test passes, with a DVOM, verify that you have 12V at the cooling fan module power circuit (red lead to the fan power circuit, black lead to a good ground). With a scan tool that can activate the cooling fans, turn them on. If there is no 12 volts at the fan, repair the wiring from the PCM or relay to the fan, or possibly a faulty PCM.
If that is okay, check that the cooling fan module is properly grounded. Connect a test light to the positive 12V battery (red terminal) and touch the other end of the test light to the ground circuit going to the cooling fan module circuit ground. Using the scan tool to actuate the cooling fan module, check if the test light illuminates each time the scan tool actuates the fan. If the test light does not illuminate, it would indicate a circuit problem. If it illuminates, wiggle the wiring harness going to the fan to see if the test light flickers, indicating an intermittent connection.
If all tests have passed so far and you continue to get a P0483 code, it would most likely indicate a faulty cooling fan module, although a faulty PCM cannot be ruled out until the fan has been replaced. If in doubt, seek assistance from a qualified automotive diagnostician. PCMs need to be programmed or calibrated to the vehicle to be installed correctly.