Engine-CodesSaturn – P1639 Saturn

P1639 Saturn Code - PCM 5 Volt Reference Voltage Circuit Condition

Quick Answer

The P1639 diagnostic trouble code (DTC) for Saturn vehicles indicates a problem with the Powertrain Control Module (PCM) 5 volt reference voltage circuit. Common causes include Faulty wiring harness or connectors, Failed sensor or component drawing excessive current, Corrosion or damage to electrical connections. 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 Saturn indicates PCM 5 Volt Reference Voltage Circuit Condition.
Common causes
Common causes include Faulty wiring harness or connectors, Failed sensor or component drawing excessive current, Corrosion or damage to electrical connections.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P1639 Saturn Description

The P1639 diagnostic trouble code (DTC) for Saturn vehicles indicates a problem with the Powertrain Control Module (PCM) 5 volt reference voltage circuit. The PCM is a crucial component of the vehicle's engine management system, responsible for controlling various functions such as fuel injection, ignition timing, and emissions. The 5 volt reference voltage circuit provides a stable voltage supply to various sensors and components within the engine system. When this circuit malfunctions, it can lead to a variety of issues that affect the vehicle's performance and drivability.

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

Common Causes of P1639 Saturn

  1. Faulty wiring harness or connectors
  2. Failed sensor or component drawing excessive current
  3. Corrosion or damage to electrical connections
  4. PCM malfunction or software issues
  5. Electrical interference or noise affecting the reference voltage signal

Symptoms of P1639 Saturn

  1. Check engine light illuminated on the dashboard
  2. Rough idling or stalling
  3. Loss of power or acceleration
  4. Poor fuel economy
  5. Engine misfires or hesitation

How to Fix P1639 Saturn

  1. Use a diagnostic scan tool to retrieve the specific sensor or component causing the issue.
  2. Inspect the wiring harness, connectors, and sensors for any visible damage or corrosion.
  3. Test the 5 volt reference voltage circuit using a multimeter to identify the faulty component.
  4. Replace the faulty sensor, wiring harness, or connector as needed.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved.

Cost to Fix P1639 Saturn

The cost of repairing a P1639 code on a Saturn vehicle can vary depending on the specific cause of the issue. In general, you can expect to pay anywhere from $100 to $300 for parts and labor. Keep in mind that diagnostic time and labor rates at auto repair shops can vary, so it's best to obtain quotes from local shops for a more accurate estimate. Additionally, the cost may be higher if the PCM needs to be replaced or if multiple components are affected.

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.

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