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P101B 2018 GMC Sierra Code - Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage

Quick Answer

The diagnostic trouble code P101B for a 2018 GMC Sierra refers to an issue with the Glow Plug Control Module Temperature Sensor 2 Circuit registering low voltage. Common causes include Faulty temperature sensor: The temperature sensor itself may be malfunctioning, providing incorrect readings, Wiring issues: Damaged or corroded wiring connections can disrupt the voltage signal, Glow plug control module failure: A malfunction in the control module can affect the sensor's readings. 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
P101B 2018 GMC Sierra indicates Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage.
Common causes
Common causes include Faulty temperature sensor: The temperature sensor itself may be malfunctioning, providing incorrect readings, Wiring issues: Damaged or corroded wiring connections can disrupt the voltage signal, Glow plug control module failure: A malfunction in the control module can affect the sensor's readings.
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 Sep 13, 2024
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Code P101B 2018 GMC Sierra Description

The diagnostic trouble code P101B for a 2018 GMC Sierra refers to an issue with the Glow Plug Control Module Temperature Sensor 2 Circuit registering low voltage. The Glow Plug Control Module is a crucial component in diesel engines, as it controls the activation of the glow plugs that help with cold starting. The temperature sensor is responsible for monitoring the temperature of the glow plug control module to ensure it operates within the optimal range.

OBDII Code P101B 2018 GMC Sierra - Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage
P101B 2018 GMC Sierra Code - Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage

Common Causes of P101B 2018 GMC Sierra

  1. Faulty temperature sensor: The temperature sensor itself may be malfunctioning, providing incorrect readings.
  2. Wiring issues: Damaged or corroded wiring connections can disrupt the voltage signal.
  3. Glow plug control module failure: A malfunction in the control module can affect the sensor's readings.
  4. Electrical issues: Problems with the vehicle's electrical system can impact the sensor's voltage readings.
  5. Environmental factors: Extreme temperatures or moisture exposure can affect sensor performance.

Symptoms of P101B 2018 GMC Sierra

  1. Hard starting: Difficulty starting the engine, especially in cold weather.
  2. Engine misfires: Rough idling or misfires due to improper glow plug operation.
  3. Decreased fuel efficiency: The engine may run less efficiently due to improper combustion.
  4. Check Engine Light: The illumination of the Check Engine Light on the dashboard.
  5. Reduced power: The vehicle may experience a loss of power, especially during acceleration.

How to Fix P101B 2018 GMC Sierra

  1. Diagnose the issue: Use a diagnostic scanner to retrieve the trouble codes and pinpoint the exact cause of the low voltage reading.
  2. Inspect the temperature sensor: Check the sensor for any visible damage or signs of malfunction.
  3. Test the wiring: Inspect the wiring connections for any damage, corrosion, or loose connections.
  4. Replace the temperature sensor: If the sensor is faulty, replace it with a new one following manufacturer guidelines.
  5. Clear the codes: After the repair, clear the trouble codes and test the vehicle to ensure the issue is resolved.

Cost to Fix P101B 2018 GMC Sierra

The cost of repairing a Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage issue can vary depending on the specific cause of the problem and the labor rates in your area. Typically, the cost of replacing a temperature sensor ranges from $100 to $200, while labor costs can range from $100 to $200 as well. Overall, the total repair cost could be around $200 to $400, but it's advisable to get a detailed quote from a trusted auto repair shop based on your vehicle's make and model. Keep in mind that rates may vary based on location, shop rates, and the extent of the repair needed.

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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 P101B 2018 GMC Sierra Code

1. What does the OBDII code P101B mean on a 2018 GMC Sierra?

P101B indicates "Glow Plug Control Module Temperature Sensor 2 Circuit Low Voltage," meaning there’s an issue with the voltage signal from the second temperature sensor in the glow plug control module.

2. What are the common symptoms of the P101B code on a 2018 GMC Sierra?

Symptoms may include difficulty starting the engine in cold weather, reduced engine performance, an illuminated check engine light, or issues with the glow plug system.

3. What causes the P101B code to appear?

Common causes include a faulty glow plug control module temperature sensor, damaged or corroded wiring, poor electrical connections, or a failed control module.

4. Can I drive my 2018 GMC Sierra with the P101B code?

While it may still be drivable, ignoring this code can lead to poor cold-start performance, potential engine damage in cold weather, and reduced fuel efficiency.

5. How do I diagnose the P101B code on a 2018 GMC Sierra?

Start by checking the wiring and connectors for damage or corrosion. Use a multimeter to test the sensor’s voltage and resistance. If these appear fine, the glow plug control module may need further inspection.

6. How is the P101B code typically repaired?

Repairs may include replacing the glow plug control module temperature sensor, repairing damaged wiring, cleaning corroded connections, or replacing the glow plug control module if necessary.

7. How much does it cost to fix the P101B code on a 2018 GMC Sierra?

Repair costs vary, but replacing the temperature sensor typically costs $100–$300, including parts and labor. Additional repairs, such as module replacement, may increase costs.

8. Can a bad battery cause the P101B code on a GMC Sierra?

Yes, a weak or failing battery can cause low voltage issues, potentially triggering the P101B code. Ensure the battery and charging system are in good working condition.

9. What tools are needed to troubleshoot the P101B code?

You’ll need an OBDII scanner, a multimeter, and possibly a wiring diagram for the glow plug control module circuit to properly diagnose the issue.

10. Does the P101B code affect engine performance?

Yes, it can affect engine performance, especially during cold starts, as the glow plug system may not function correctly to assist in warming up the engine.

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