Error Code P0527 is defined as Fan Speed Sensor Circuit Range or Performance Issue. This means there’s range or performance problem on the fan speed sensor circuit, likely caused by a defective temperature sensor or damaged wires.

This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

Some vehicles come with a special sensor called cooling fan speed sensor to detect movement during the operation of the vehicle. This sensor determines the fan clutch or verifies the fan speed as commanded by the PCM (powertrain control module, also known as the ECM or engine control module), to match the actual fan speed detected on an electric fan equipped vehicle.

This sensor has three wires that use a 5V reference source coming from the PCM, a ground wire, and a signal wire to the PCM to read the fan speed.

This code is triggered when the PCM detects that the actual fan speed doesn’t match with the commanded or desired speed.

Other related electric fan error codes include:

  • Error Code P0526
  • Error Code P0529
  • Error Code P0529

Common Symptoms

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

  • Overheating
  • Vehicle running hotter than usual
  • A/C not working

Possible Causes

There are many reasons for the clutch or electric fan to not run at commanded or desired speed, such as:

  • Defective cooling fan motor
  • Defective cooling fan relay
  • Defective engine coolant temperature sensor
  • Broken, frayed, or shorted wires at the engine coolant temperature sensor
  • Broken, frayed, or shorted wires at the fan speed sensor
  • Corroded, damaged, or loose connectors at the engine coolant temperature sensor
  • Corroded, damaged, or loose connectors at the fan speed sensor
  • Defective electric fan
  • Defective fan clutch
  • Defective fan speed sensor
  • Blown fuse

How to Check

As with most codes, the first step for diagnosis for this would be to check if there are other codes present in the PCM as well. These codes should be addressed in the order that they appear. Collect these trouble codes and record their freeze frame data.

Next, check the cooling fan assembly and look for signs of damages in wires, such as broken, frayed, or shorted wires. Repair or replace as necessary. The same goes for the cooling fan assembly connectors – look for signs of damage, corrosion, and bent pins.

Next, check the relay and fuses of the fan motor. Repair or replace as necessary.

Then, clear the codes and test drive the vehicle to see if the code comes back.

If the code comes back, check the engine coolant temperature sensor for breakage, frayed, or shorts in the wiring. Repair or replace as necessary. Do the same for the connectors of the engine coolant temperature sensor – look for bent pins, corrosion, or damages, and do the necessary repair or replacement.

Then, clear the codes and take the vehicle for a test drive again. If the code comes back, and the vehicle has a high or low-pressure switch for the A/C or fan, then check it for proper operation. Replace this component as necessary.

Clear the code and take the vehicle for a test drive. If the code comes back again, then it’s time to look at the PCM. Make sure there’s proper wiring.

How to Fix

Depending on the diagnosis, common repairs for this code include:

  • Replacement of engine coolant temperature sensor
  • Repair or replacement of wiring issues in engine coolant temperature sensor
  • Repair or replacement of wiring connector issues in engine coolant temperature sensor
  • Replacement of fan speed sensor’s wiring issues
  • Replacement of fan speed sensor connector issues
  • Replacement of cooling fan relay
  • Replacement of cooling fan motor
  • Replacement of electric fan
  • Replacement of fan clutch
  • Replacement of blown fuse
  • Replacement of fan speed sensor

The most common mistake in addressing this code is replacing the cooling fan assembly when the problem is only at the wiring, bad fuse, or defective relay. Thus, it pays to check thoroughly to avoid unnecessary and expensive replacements.

Also, it is rare for the PCM to go bad, but it is possible.