P0642 2018 GMC Sierra Code - 5 Volt Reference 1 Circuit Low Voltage
Quick Answer
The Engine Control Module (ECM) has four (4) internal 5 Volt reference circuits (Some models have two (2) internal 5 Volt reference circuits). Common causes include Faulty Sensor on 5 Volt circuit, Sensor on 5 Volt circuit harness is open or shorted, Sensor on 5 Volt 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 2018 GMC Sierra indicates 5 Volt Reference 1 Circuit Low Voltage.
- Common causes
- Common causes include Faulty Sensor on 5 Volt circuit, Sensor on 5 Volt circuit harness is open or shorted, Sensor on 5 Volt 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 2018 GMC Sierra Description
What are the Possible Causes of the DTC P0642 2018 GMC Sierra?
- Faulty Sensor on 5 Volt circuit
- Sensor on 5 Volt circuit harness is open or shorted
- Sensor on 5 Volt circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0642 2018 GMC Sierra?
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.
Code Tech Notes
The 5 Volt reference 1 circuit provides 5 Volt to the following sensors: (Some models may have different sensors, please consult the factory service manual for the list of sensors for your model and year)
- Air conditioning (A/C) refrigerant pressure sensor
- Camshaft position sensor
- Engine oil pressure sensor
- Fuel pressure sensor
- Fuel rail pressure sensor
- Fuel tank pressure sensor
- Multifunction intake air sensor
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0642 2018 GMC Sierra 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.
Need more information about the P0642 2018 GMC Sierra code?
Need more information on how to fix the P0642 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0642 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P0642 2018 GMC Sierra Code
1. What does the OBDII code P0642 mean on a 2018 GMC Sierra?
P0642 indicates a low voltage condition in the 5-volt reference 1 circuit, which provides power to various sensors in the vehicle.
2. What are the common symptoms of code P0642 in a 2018 GMC Sierra?
Symptoms may include poor engine performance, reduced fuel efficiency, illumination of the check engine light, erratic sensor readings, or difficulty starting the vehicle.
3. What causes the P0642 code to appear in a 2018 GMC Sierra?
Common causes include a short in the 5-volt reference circuit, a faulty sensor drawing excess power, a damaged wiring harness, or a malfunctioning engine control module (ECM).
4. Can a faulty sensor trigger the P0642 code?
Yes, a malfunctioning sensor that uses the 5-volt reference circuit can cause the voltage to drop, triggering the P0642 code.
5. How can I diagnose the P0642 code on my 2018 GMC Sierra?
Start by checking for damaged or shorted wiring in the 5-volt reference circuit, inspect connected sensors for faults, and test the ECM for proper operation.
6. Is it safe to drive my 2018 GMC Sierra with a P0642 code?
Driving with the P0642 code is not recommended, as it can lead to erratic engine performance and potential damage to other components.
7. Which sensors rely on the 5-volt reference circuit in a 2018 GMC Sierra?
Sensors such as the throttle position sensor (TPS), manifold absolute pressure (MAP) sensor, and mass airflow (MAF) sensor commonly use the 5-volt reference circuit.
8. How is the P0642 code fixed in a 2018 GMC Sierra?
Repairs may include replacing a faulty sensor, repairing damaged wiring, or, in rare cases, replacing the ECM.
9. Can a dead battery cause the P0642 code to appear?
While unlikely, a weak or failing battery can cause voltage irregularities, which might contribute to electrical issues in the system.
10. How much does it typically cost to fix the P0642 code on a 2018 GMC Sierra?
Repair costs can vary widely, ranging from $100 to $500, depending on whether a sensor, wiring repair, or ECM replacement is required.
Discuss the causes and fixes for P0642 2018 GMC Sierra OBDII Code
Code P0642 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
