Error Code P0493 is defined as Fan Overspeed, which basically means the electric cooling fan system is having a voltage problem, which could be caused by multiple things, such as defective fan motor, fan relay problems, or faulty fan fuse, wiring, or sensor.


This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system or vehicles made from 1996 up to the present. It is usually found among Acura, BMW, Buick, Citroen, Chevrolet, Dodge, Ford, Peugeot, and Toyota. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

Generally, the fan is mounted on the radiator, and it works by regulating the temperature of the engine by cooling the coolant in the radiator.

The PCM (powertrain control module, also known as ECM or engine control module in other makes) monitors and controls multiple sensors to keep the right temperature of the engine. One of which is the fan, which it switches on as the engine gets high (i.e. during idle at traffic), and off when there is sufficient airflow to keep the temperature down (cruising down the highway).

When the PCM detects an overspeed condition if the fan is spinning beyond or below the parameters set by the manufacturer, the Error Code P0493 will be set, activating the Check Engine light.

This code could be caused by a bad ground or a defective fan.

Other related trouble codes include:

Common Symptoms

As with other error codes, this code illuminates the Check Engine light and registers the code to the vehicle’s memory. Other common symptoms would include:

  • Engine overheating
  • Engine misfiring
  • Engine noises
  • Stalling
  • Increase in fuel consumption

Possible Causes

Common causes of this code include:

  • Defective electric fan motor
  • Defective electric fan relay
  • Blown electric fuse
  • Faulty wiring and connectors in the electrical connectors of the fan
  • Damaged engine coolant temperature sensor

How to Check

This code can be easy to diagnose. First and foremost, technicians start their diagnosis by conducting a visual inspection of the fan, and all its connected wirings, electrical connectors, associated fuses, and control relay, and repair or replace as necessary.

If the wiring system seems fine, they will proceed on checking the fan by triggering the fan to power by either jumping the relay, sending a 12V straight to the fan, or trigger it through the air conditioning. They can determine the problem when they find out when and in under what conditions the fan starts to turn.

For example, if the fan turns on when the relay is jumped but doesn’t when the AC is activated, then that means the problem is caused by a bad relay.

If the fan doesn’t turn on at all, then the motor has gone bad, which means it must be replaced.

The key to a successful repair of this code is confirming if the fan is in good condition, and then move on to the next step, which is the relay.

How to Fix

Common repairs for this code include:

  • Replacement of the electric cooling fan relay
  • Replacement of the electric cooling fan
  • Repair or replacement of the damaged wiring or issues in the electrical connectors of the electric cooling fan
  • Replacement of the blown fuse

The most common mistake in tackling this error code is rushing to replace the fan and the relay. Thus, it pays to diagnose each component thoroughly.

Though this code will not usually cause a serious problem, you will have to be extra careful in slow driving conditions with during high ambient temperature. Though it’s unlikely for the engine to stop working without the electric cooling fan, a hot engine will not perform at its best.