P0642 Code - Sensor Reference Voltage 'A' Circuit Low
Quick Answer
The control module has 2 internal 5-volt reference buses called "5-volt reference 1" and"5-volt reference 2". Common causes include Faulty Engine Control Module (ECM), ECM harness is open or shorted, ECM 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 indicates Sensor Reference Voltage 'A' Circuit Low.
- Common causes
- Common causes include Faulty Engine Control Module (ECM), ECM harness is open or shorted, ECM 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.
Code P0642 Description
What are the Possible Causes of the DTC P0642?
- Faulty Engine Control Module (ECM)
- ECM harness is open or shorted
- ECM circuit poor electrical connection
- Shorted sensor on 5 volt circuit
How to Fix the DTC P0642?
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 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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Information for Specific Makes
- P0642 Audi — Sensor Voltage Circuit 'A' Low Voltage
- P0642 Buick — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Cadillac — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Chevrolet — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Chrysler — Sensor Reference Voltage 1 Circuit Low
- P0642 Dodge — Sensor Reference Voltage 1 Circuit Low
- P0642 Ford — Sensor Reference Voltage 'A' Circuit Low
- P0642 GMC — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Hyundai — Sensor Reference Voltage 'A' Circuit Low
- P0642 Isuzu — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Jeep — Sensor Reference Voltage 1 Circuit Low
- P0642 KIA — Sensor Reference Voltage 'A' Circuit Low
- P0642 Lincoln — Sensor Reference Voltage 'A' Circuit Low
- P0642 Mercury — Sensor Reference Voltage 'A' Circuit Low
- P0642 Mitsubishi — Throttle Position Sensor Power Supply
- P0642 Suzuki — 5 Volt Reference 1 Circuit Low Voltage
- P0642 Volkswagen — Sensor Reference Voltage 'A' Circuit Low
Frequently Asked Questions about P0642 Code
1. What are the common symptoms of OBDII code P0642 (Sensor Reference Voltage 'A' Circuit Low)?
The common symptoms of P0642 may include engine stalling, rough idling, poor acceleration, and illuminated Check Engine Light.
2. What are the possible causes of OBDII code P0642?
Possible causes of P0642 include a faulty sensor, damaged wiring or connectors in the sensor circuit, low battery voltage, or a problem with the engine control module (ECM).
3. How does a low sensor reference voltage affect the vehicle's performance?
A low sensor reference voltage can disrupt the proper functioning of sensors, leading to incorrect data being sent to the ECM. This can result in poor engine performance and potential drivability issues.
4. Can driving with OBDII code P0642 cause further damage to the vehicle?
Continuing to drive with code P0642 may not immediately cause major damage, but it can lead to poor fuel efficiency, increased emissions, and potential long-term engine issues if left unresolved.
5. How is OBDII code P0642 diagnosed?
Diagnosing code P0642 typically involves using a diagnostic scanner to retrieve the code, checking the sensor's voltage output, inspecting the wiring and connectors for damage, and testing the sensor's resistance.
6. What are some repair tips for fixing OBDII code P0642?
Repair tips for P0642 may include replacing the faulty sensor, repairing damaged wiring or connectors, ensuring proper battery voltage, and reprogramming or replacing the ECM if necessary.
7. Is it safe to drive with the Check Engine Light on due to code P0642?
While driving with the Check Engine Light on due to P0642 may not pose an immediate safety risk, it is recommended to address the issue promptly to prevent potential performance issues and further damage to the vehicle.
8. Can I reset the Check Engine Light after fixing OBDII code P0642?
After resolving the issue causing P0642 and ensuring the problem is fixed, you can reset the Check Engine Light using a diagnostic scanner to clear the trouble code from the vehicle's memory.
9. How much does it typically cost to repair OBDII code P0642?
The cost to repair P0642 can vary depending on the root cause of the issue, the type of sensor involved, and whether any additional repairs or parts replacements are needed. It's advisable to consult a mechanic for a more accurate estimate.
10. Are there any preventive measures to avoid OBDII code P0642 in the future?
To help prevent code P0642, it's essential to perform regular vehicle maintenance, address any sensor issues promptly, and ensure proper battery voltage to minimize the risk of sensor reference voltage circuit problems.
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