AutoCodes – Volkswagen – P0642 Volkswagen

P0642 Volkswagen Code - Sensor Reference Voltage 'A' Circuit Low

Quick Answer

This fault code is stored in the Engine Control Module (ECM) when a malfunction occurs with the sensor supply voltage circuit. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module circuit poor electrical connection. 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: P0642 Volkswagen indicates Sensor Reference Voltage 'A' Circuit Low.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module circuit poor electrical connection.
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 41,722

How popular is this code, among other codes? Medium

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 Jul 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0642 Volkswagen Description

This fault code is stored in the Engine Control Module (ECM) when a malfunction occurs with the sensor supply voltage circuit. The Engine Control Module outputs a 5-volt supply voltage to certain sensors. Many components share the same 5-volt supply. If fault codes exist for multiple components that operate with a 5-volt supply the wiring from the Engine Control Module and the Engine Control Module itself should be tested. Also, each component should be disconnected in turn to identify a faulty component pulling down the supply circuit. The Diagnostic Trouble Code (DTC) will set when the Engine Control Module has detected the sensor 5-volt reference circuit voltage is lower than expected.

OBDII Code P0642 Volkswagen - Sensor Reference Voltage 'A' Circuit Low - AutoCodes.com — P0642 Volkswagen Code - Sensor Reference Voltage 'A' Circuit Low

What does this mean?

What are the Possible Causes of the DTC P0642 Volkswagen?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection
Shorted sensor on 5-volt circuit

How to Fix the DTC P0642 Volkswagen?

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 P0642 Volkswagen 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 P0642 Volkswagen Code

1. What does OBDII code P0642 mean for my Volkswagen?

The code P0642 indicates a fault in the Sensor Reference Voltage 'A' Circuit, specifically that the voltage is reading lower than expected.

2. What are the common symptoms of OBDII code P0642 in a Volkswagen?

Common symptoms include issues with engine performance, rough idling, stalling, and in some cases, the vehicle may not start at all.

3. What are the possible causes of OBDII code P0642 in a Volkswagen?

Potential causes include a faulty sensor, damaged wiring or connectors in the reference voltage circuit, or problems with the Engine Control Module (ECM).

4. How can I diagnose the Sensor Reference Voltage 'A' Circuit Low issue in my Volkswagen?

A diagnostic scan tool can be used to read the code and pinpoint the exact source of the problem, whether it's a sensor malfunction or a wiring issue.

5. Can I continue driving my Volkswagen with OBDII code P0642?

It is not recommended to drive your vehicle with this code present, as it can lead to further damage or potential safety hazards. It's best to address the issue promptly.

6. Is it possible to repair OBDII code P0642 in a Volkswagen by myself?

Depending on your experience and tools available, you may be able to address this issue yourself by replacing the faulty sensor or repairing damaged wiring. However, professional help is recommended for accurate diagnosis and repair.

7. What is the typical cost to repair OBDII code P0642 in a Volkswagen?

The cost of repair can vary based on the specific cause of the issue. It could range from a simple sensor replacement costing around $100 to more complex repairs involving the ECM, which could cost several hundred dollars.

8. How urgent is it to fix OBDII code P0642 in my Volkswagen?

It is advisable to address this issue as soon as possible to prevent any further damage to your vehicle and ensure optimal performance.

9. Are there any preventive measures to avoid OBDII code P0642 in the future?

Regular vehicle maintenance, including checking the sensors and wiring for any signs of wear or damage, can help prevent issues like P0642 from occurring.

10. Can a P0642 fault code clear on its own in a Volkswagen?

The fault code may sometimes clear on its own if the issue was intermittent. However, it's best to diagnose and repair the underlying problem to prevent it from recurring.