AutoCodes – Buick – P1642 Buick

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

Quick Answer

Ignition voltage is supplied to the Cooling Fan relay coil. Common causes include Faulty Cooling Fan Relay, Cooling Fan Relay harness is open or shorted, Cooling Fan Relay circuit poor electrical component. 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 Buick indicates Fan Control Relay 2 and 3 Control Circuit.
Common causes: Common causes include Faulty Cooling Fan Relay, Cooling Fan Relay harness is open or shorted, Cooling Fan Relay circuit poor electrical component.
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.

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Code Popularity 4,381

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 04, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1642 Buick Description

Ignition voltage is supplied to the Cooling Fan relay coil. The Powertrain Control Module (PCM) controls the relay by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component ON, the voltage of the control circuit should be low (near 0 volts). When the PCM is commanding the control circuit to a component OFF, the voltage potential of the circuit should be high (near battery voltage). If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the code to set.
The relay is used to control the high current flow to the cooling fan motors. This allows the PCM driver to only have to handle the relatively low current used by the relay.

OBDII Code P1642 Buick - Fan Control Relay 2 and 3 Control Circuit - AutoCodes.com — P1642 Buick Code - Fan Control Relay 2 and 3 Control Circuit

What does this mean?

What are the Possible Causes of the DTC P1642 Buick?

Faulty Cooling Fan Relay
Cooling Fan Relay harness is open or shorted
Cooling Fan Relay circuit poor electrical component

How to Fix the DTC P1642 Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1642 Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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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 Buick Code

1. What are the common symptoms of OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in a Buick?

- Common symptoms include overheating of the engine, erratic fan operation, and potential illumination of the check engine light.

2. What are the possible causes of OBDII code P1642 in a Buick related to the Fan Control Relay 2 and 3 Control Circuit?

- Causes may include a faulty fan control relay, wiring issues, a malfunctioning cooling fan motor, or a problem with the engine coolant temperature sensor.

3. How can I diagnose OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in my Buick?

- Diagnosis typically involves checking the fan control relays, inspecting the wiring for any damage, testing the cooling fan motor, and verifying the operation of the engine coolant temperature sensor.

4. Is it safe to continue driving my Buick with OBDII code P1642 related to the Fan Control Relay 2 and 3 Control Circuit?

- It is not recommended to drive your Buick with this code as it can lead to engine overheating and potential damage. It is best to address the issue promptly.

5. Can I repair OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in my Buick myself?

- Depending on your automotive knowledge and skills, you may be able to perform the repair yourself by replacing the faulty components, such as the fan control relay or the cooling fan motor.

6. Are there any specific repair tips for fixing OBDII code P1642 in a Buick related to the Fan Control Relay 2 and 3 Control Circuit?

- When repairing this issue, make sure to carefully inspect all related components, use the appropriate tools for testing and replacement, and follow the manufacturer's guidelines for proper repair procedures.

7. How much does it typically cost to repair OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in a Buick?

- The cost of repair can vary depending on the specific cause of the issue and whether you perform the repair yourself or take your Buick to a professional mechanic. Costs may range from a few hundred to a thousand dollars.

8. Can a faulty engine coolant temperature sensor trigger OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in a Buick?

- Yes, a malfunctioning engine coolant temperature sensor can disrupt the operation of the cooling fans, leading to the triggering of this OBDII code in a Buick.

9. Are there any preventive measures to avoid encountering OBDII code P1642 related to the Fan Control Relay 2 and 3 Control Circuit in a Buick?

- Regular maintenance, such as checking the cooling system components, inspecting wiring for damage, and monitoring the engine temperature, can help prevent issues that may trigger this code in your Buick.

10. How urgent is it to address OBDII code P1642 for the Fan Control Relay 2 and 3 Control Circuit in a Buick?

- It is important to address this issue promptly to prevent engine overheating and potential damage. Ignoring this code can lead to more severe problems and costly repairs down the line.