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P1639 Buick Code - PCM 5 Volt Reference Voltage Circuit Condition

Quick Answer

The P1639 Buick code indicates a problem with the PCM (Powertrain Control Module) 5 Volt reference voltage circuit. Common causes include Faulty PCM, Short circuit in the 5-volt reference circuit, Damaged wiring or connectors. 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
P1639 Buick indicates PCM 5 Volt Reference Voltage Circuit Condition.
Common causes
Common causes include Faulty PCM, Short circuit in the 5-volt reference circuit, Damaged wiring or connectors.
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 Aug 19, 2024
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Code P1639 Buick Description

The P1639 Buick code indicates a problem with the PCM (Powertrain Control Module) 5 Volt reference voltage circuit. The PCM provides a 5-volt reference signal to various sensors and components in the vehicle, which is crucial for their proper operation. When this circuit malfunctions, it can lead to issues with sensor readings, engine performance, and overall vehicle operation.

OBDII Code P1639 Buick - PCM 5 Volt Reference Voltage Circuit Condition
P1639 Buick Code - PCM 5 Volt Reference Voltage Circuit Condition

Common Causes of P1639 Buick

  1. Faulty PCM
  2. Short circuit in the 5-volt reference circuit
  3. Damaged wiring or connectors
  4. Failed sensor or component drawing excessive voltage
  5. Corrosion or contamination in the circuit

Symptoms of P1639 Buick

  1. Check engine light illuminated
  2. Engine stalling or hesitation
  3. Inaccurate or erratic gauge readings
  4. Poor fuel economy
  5. Difficulty starting the engine

How to Fix P1639 Buick

  1. Diagnose the issue using a scan tool to pinpoint the exact cause of the problem.
  2. Inspect the wiring harness and connectors for any signs of damage or corrosion.
  3. Test the sensors and components connected to the 5-volt reference circuit to identify any faulty ones.
  4. Replace the faulty component, repair any damaged wiring, or replace the PCM if necessary.
  5. Clear the diagnostic trouble codes and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1639 Buick

The repair cost for a P1639 Buick code can vary depending on the specific cause of the issue and the extent of the repairs needed. On average, the cost of parts and labor for this repair could range from $200 to $500. However, it is essential to keep in mind that labor rates and part prices can vary significantly based on location, vehicle make and model, and the specific repair shop. It is recommended to obtain quotes from multiple repair shops to get a more accurate estimate for your particular situation.

When is the Code Detected?

If the voltage is out of tolerance, the Powertrain Control Module (PCM) will set DTC P1639.

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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 P1639 Buick Code

1. What are the common symptoms of OBDII code P1639 on a Buick related to the PCM 5 Volt Reference Voltage Circuit Condition?

- Common symptoms include engine stalling, rough idling, loss of power, and issues with various electrical components.

2. What are the possible causes of OBDII code P1639 in a Buick, indicating a PCM 5 Volt Reference Voltage Circuit Condition?

- Possible causes may include a faulty PCM, damaged wiring or connectors in the 5 volt reference circuit, or a malfunctioning sensor.

3. How can I diagnose the PCM 5 Volt Reference Voltage Circuit Condition issue causing OBDII code P1639 in my Buick?

- Diagnosing this issue typically involves checking the wiring and connectors for damage, testing the sensors connected to the 5 volt reference circuit, and inspecting the PCM for faults.

4. Can a DIY enthusiast repair the PCM 5 Volt Reference Voltage Circuit Condition issue triggering OBDII code P1639 in a Buick?

- While some basic troubleshooting steps can be performed by a DIY enthusiast, resolving this issue often requires advanced diagnostic equipment and knowledge. It's recommended to consult a professional mechanic.

5. Is it safe to continue driving my Buick with OBDII code P1639 due to the PCM 5 Volt Reference Voltage Circuit Condition?

- It is not recommended to drive the vehicle with this issue, as it can lead to further damage and potential safety hazards. It's best to address the problem promptly.

6. Are there any specific sensors commonly associated with triggering OBDII code P1639 related to the PCM 5 Volt Reference Voltage Circuit Condition in a Buick?

- Sensors commonly linked to this issue include the throttle position sensor (TPS), manifold absolute pressure (MAP) sensor, and engine coolant temperature (ECT) sensor.

7. How much does it typically cost to repair the PCM 5 Volt Reference Voltage Circuit Condition causing OBDII code P1639 in a Buick?

- The cost of repair can vary depending on the exact cause of the issue and the labor rates in your area. It's advisable to obtain quotes from reputable mechanics.

8. Can a weak battery or alternator problem trigger OBDII code P1639 due to the PCM 5 Volt Reference Voltage Circuit Condition in a Buick?

- Yes, a weak battery or alternator issue can affect the 5 volt reference circuit and potentially trigger this OBDII code. It's important to ensure the electrical system is in good condition.

9. Will resetting the OBDII code P1639 related to the PCM 5 Volt Reference Voltage Circuit Condition in my Buick make the problem go away?

- Resetting the code may temporarily clear the warning light, but it will not fix the underlying issue causing the fault code. Proper diagnosis and repair are necessary.

10. How long does it typically take to repair the PCM 5 Volt Reference Voltage Circuit Condition leading to OBDII code P1639 in a Buick?

- The repair time can vary based on the complexity of the issue and the availability of parts. In some cases, it may be resolved quickly, while in others, it could take several hours or more.

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