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Engine-Codes – Generic – P1642

P1642 Code - Fan Control Relay 2 and 3 Control Circuit

Quick Answer

The diagnostic trouble code P1642 indicates a problem with the control circuit for Fan Control Relay 2 and 3 in the vehicle. Common causes include Faulty relay: The fan control relay 2 or 3 may be faulty or damaged, causing the circuit to malfunction, Wiring issues: There could be a wiring problem, such as a short circuit or open circuit, in the fan control relay circuit, Blown fuse: A blown fuse in the fan control relay circuit can also trigger this code. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1642 indicates Fan Control Relay 2 and 3 Control Circuit.
Common causes
Common causes include Faulty relay: The fan control relay 2 or 3 may be faulty or damaged, causing the circuit to malfunction, Wiring issues: There could be a wiring problem, such as a short circuit or open circuit, in the fan control relay circuit, Blown fuse: A blown fuse in the fan control relay circuit can also trigger this code.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 06, 2024
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Code P1642 Description

The diagnostic trouble code P1642 indicates a problem with the control circuit for Fan Control Relay 2 and 3 in the vehicle. This relay is responsible for controlling the operation of the cooling fans in the vehicle's cooling system. When this code is triggered, it means that there is a malfunction in the circuit that controls the operation of these fans. This can lead to issues with the engine cooling system, which can result in overheating and potential engine damage if not addressed promptly.

OBDII Code P1642 - Fan Control Relay 2 and 3 Control Circuit
P1642 Code - Fan Control Relay 2 and 3 Control Circuit

Common Causes of P1642

  1. Faulty relay: The fan control relay 2 or 3 may be faulty or damaged, causing the circuit to malfunction.
  2. Wiring issues: There could be a wiring problem, such as a short circuit or open circuit, in the fan control relay circuit.
  3. Blown fuse: A blown fuse in the fan control relay circuit can also trigger this code.
  4. Failed cooling fan motor: If the cooling fan motors are not functioning properly, it can impact the operation of the fan control relay circuit.

Symptoms of P1642

  1. Engine overheating: Since the cooling fans are not functioning properly, the engine may overheat, especially in heavy traffic or at low speeds.
  2. A/C not working: The air conditioning system may not work properly if the cooling fans are not operating correctly, leading to poor cooling performance.
  3. Check engine light: The check engine light may illuminate on the dashboard due to the detected issue with the fan control relay circuit.
  4. Poor fuel efficiency: If the engine is running hotter than normal due to cooling fan issues, it can lead to decreased fuel efficiency.

How to Fix P1642

  1. Diagnose the issue: Use a diagnostic tool to pinpoint the exact cause of the code P1642, whether it's a faulty relay, wiring issue, blown fuse, or fan motor problem.
  2. Replace faulty components: If the relay, wiring, or fuse is found to be the issue, replace the faulty components with new ones.
  3. Test the cooling fans: Check the operation of the cooling fans to ensure they are functioning properly after the repair.
  4. Clear the trouble code: Once the repair is completed, clear the diagnostic trouble code from the vehicle's computer system to reset the check engine light.

Cost to Fix P1642

The cost of repairing the fan control relay 2 and 3 control circuit can vary depending on the specific cause of the issue and the labor rates in your area. On average, the cost of parts for this repair can range from $50 to $200, while the labor cost can be between $100 and $300. Therefore, the total repair cost may range from $150 to $500. Keep in mind that these are rough estimates, and actual costs may vary. It's recommended to consult with a mechanic or auto repair shop to get a more accurate cost estimate for your specific vehicle.

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Code P1642 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1642 Code

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  • have P1642 code, performance not effected, been approx 2500 miles with new fuel pump.. code says fuel pump monitor circuit high input ??

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