P0482 indicates the engine computer (PCM/ECM) has detected an electrical fault in the control circuit for the third cooling fan or fan stage. This usually means an open, short to power/ground, or incorrect voltage is preventing normal command of the fan. It does not mean the engine is overheating by itself, but the fan may not operate when needed.
The relay or solid-state driver that switches power to the third fan is the component most often at fault, due to burned contacts, coil failure, or internal driver damage.
Open, shorted, corroded, or chafed wires between the PCM, relay, and fan can produce this code, especially in harnesses near hot or moving parts.
An excessive current draw, seized fan motor, or failed speed resistor can pull the control circuit outside expected voltage and set the code.
A missing power feed or ground to the relay or fan can cause the PCM to see an abnormal circuit voltage and store P0482.
Although possible, failure of the PCM fan-control output is uncommon; this should only be considered after the relay, wiring, and fan motor have been ruled out.
Short trips are usually okay, but avoid heavy loads, stop-and-go traffic, and towing until the fan circuit is repaired, because the engine may overheat if the fan does not operate.
Usually no. The PCM is one of the least likely causes. Most cases are due to a bad relay, wiring fault, or fan motor problem, so the circuit should be diagnosed before replacing the computer.
Yes, if testing confirms the relay is bad. Replacing parts without diagnosis can waste effort if the real problem is wiring or the fan motor.
The fault may be intermittent. Wiggle-test the harness and monitor live data while commanding the fan, because a poor connection can set the code only under certain conditions.