2018 Lexus IS350 Radiator Fan Isn't Working

Diagnosing the Causes of a Non-Functioning Radiator Fan in Your 2018 Lexus IS350 and How to Fix It

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Reviewed by
Devin Cabugcal
Written by RepairPal Car Genius
Updated January 14, 2025
0%
34% chance it's the
Fan Motor or Clutch
0%
28% chance it's the
Fan Relay or Fuse
0%
23% chance it's the
Temp Sensor or Fan Control Module
0%
15% chance it's
Something else
The most common reasons a 2018 Lexus IS350 radiator fan isn't working are the fan assembly, the fan clutch, or the coolant temperature sensor.
  • Fan Motor or Clutch: A faulty fan motor or a malfunctioning fan clutch can result in inadequate cooling, causing the engine to overheat.
  • Fan Relay or Fuse: A faulty fan relay or blown fuse can prevent the cooling fan from operating, leading to engine overheating.
  • Temp Sensor or Fan Control Module: A faulty temperature sensor or fan control module can result in incorrect readings, causing the engine to overheat or the cooling fan to operate improperly.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2018 Lexus IS350 radiator fan isn't working?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Over time serpentine belts stretch, crack, and the ribs that ride on the accessory pulleys being to wear smooth. A squealing noise that increases with engine speed or as engine driven accessories are turned on may be noted. The noise is caused by the belt slipping on the pulleys, insufficiently driving them. Ineffective air conditioning, a battery warning light, or intermittent power steering assist can result from this.

»MORE: Symptoms of a bad serpentine belt

The bad thermostat can cause two different sets of problems, depending on whether it's stuck open or stuck closed.

A thermostat that is stuck open can cause the engine to run colder than normal and turn on the check engine light. It may also cause poor fuel mileage and the heater to blow cool air.

A thermostat that is stuck closed will cause the vehicle to overheat. If a new thermostat doesn't resolve engine temperature problems, the cooling system needs to be checked for other issues.

» LEARN MORE: Signs of a bad thermostat, and how to fix it

When the engine coolant temperature sensor fails, it will send inaccurate information to the vehicle’s computer, causing the computer to react to false operating conditions. This will cause the engine to consume more fuel than normal, depleting fuel mileage, and causing black, sooty smoke from the engine under moderate to heavy acceleration. The check engine light will illuminate, and on-board diagnostic trouble codes may be stored for exhaust and emission system failure, fuel delivery system failure, and engine cooling system failure. Overheating may also occur, as the coolant sensor may be leaking fluid out of the engine, creating a an air pocket in the system.

What are the steps to diagnose the non-functioning radiator fan in a 2018 Lexus IS350?

To effectively diagnose a non-functioning radiator fan in your 2018 Lexus IS350, begin with a systematic approach that prioritizes simpler checks before delving into more complex diagnostics. Start by examining the fuse associated with the radiator fan; a blown fuse is a common and easily fixable issue that can halt fan operation. If the fuse is intact, proceed to inspect the relay, as a malfunctioning relay can also prevent the fan from activating. Next, test the fan motor directly by applying power to it; if the motor spins, it indicates that the fan itself is operational. If the fan does not work, further investigation is needed. Additionally, check the temperature sensor, which is crucial for signaling the fan to turn on when the engine reaches a certain temperature. Ensure that this sensor is functioning correctly. Don’t overlook the wiring and connections; loose or damaged wires can disrupt the fan's operation. Finally, using a diagnostic scanner can help identify any error codes related to the radiator fan system, providing insight into more complex issues. By following this structured diagnostic approach, you can efficiently identify and resolve the problem with your radiator fan.

What are the common problems that could cause the radiator fan to stop working in a 2018 Lexus IS350?

When troubleshooting a non-functioning radiator fan in a 2018 Lexus IS350, it's essential to consider several common problems that could be at play. A faulty fan motor is often the primary culprit, as a malfunctioning motor will prevent the fan from spinning and adequately cooling the radiator. Additionally, a blown fuse can disrupt the power supply to the fan, rendering it inoperative. It's also crucial to check the temperature sensor, as a faulty sensor may provide incorrect readings, leading to the fan not activating when necessary. Wiring issues, such as frayed wires or loose connections, can further complicate the situation by interrupting the electrical flow. Low coolant levels can trigger safety mechanisms that stop the fan from operating, so ensuring proper coolant levels is vital. Lastly, a malfunctioning fan relay can prevent the fan from turning on and off as intended. Addressing these issues promptly is crucial to avoid overheating and potential engine damage, making it advisable for DIYers to conduct a thorough inspection or consult a qualified mechanic if needed.

How urgent is it to address the non-working radiator fan in a 2018 Lexus IS350?

Addressing a non-working radiator fan in a 2018 Lexus IS350 is an urgent matter that should not be overlooked. The radiator fan plays a vital role in maintaining optimal engine temperature by dissipating heat from the radiator. When this fan fails, the engine is at risk of overheating, which can lead to severe consequences such as engine shutdown or even complete seizure. These scenarios not only result in costly repairs but can also cause catastrophic damage, including a blown head gasket or warped cylinder head. Furthermore, neglecting this issue can adversely affect the vehicle's overall performance and fuel efficiency. Therefore, it is crucial for DIY enthusiasts to prioritize the repair of a malfunctioning radiator fan to prevent potential engine damage and ensure the longevity and reliability of their Lexus IS350.

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