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Engine-Codes – GMC – P0546 2018 GMC Sierra

P0546 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 1 Circuit High Voltage

Quick Answer

The P0546 diagnostic trouble code (DTC) for a 2018 GMC Sierra refers to the Exhaust Gas Temperature Sensor 1 Circuit High Voltage. Common causes include Faulty Exhaust Gas Temperature Sensor: The sensor itself may be malfunctioning, leading to high voltage readings, Damaged Wiring or Connectors: Corrosion or damage to the wiring or connectors connected to the sensor can cause high voltage issues, ECM Malfunction: A malfunctioning ECM can also send incorrect signals to the sensor, resulting in high voltage readings. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means
P0546 2018 GMC Sierra indicates Exhaust Gas Temperature Sensor 1 Circuit High Voltage.
Common causes
Common causes include Faulty Exhaust Gas Temperature Sensor: The sensor itself may be malfunctioning, leading to high voltage readings, Damaged Wiring or Connectors: Corrosion or damage to the wiring or connectors connected to the sensor can cause high voltage issues, ECM Malfunction: A malfunctioning ECM can also send incorrect signals to the sensor, resulting in high voltage readings.
Severity
Moderate - service should be scheduled soon.
Can I drive?
The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
What is this?
Table of contents Created and updated by William Orellana on Sep 16, 2024
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Code P0546 2018 GMC Sierra Description

The P0546 diagnostic trouble code (DTC) for a 2018 GMC Sierra refers to the Exhaust Gas Temperature Sensor 1 Circuit High Voltage. This code indicates that the exhaust gas temperature sensor is detecting a voltage that is higher than the specified range. The exhaust gas temperature sensor plays a crucial role in monitoring the temperature of the exhaust gases leaving the engine. This information is essential for the engine control module (ECM) to adjust fuel delivery and optimize engine performance.

OBDII Code P0546 2018 GMC Sierra - Exhaust Gas Temperature Sensor 1 Circuit High Voltage
P0546 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 1 Circuit High Voltage

Common Causes of P0546 2018 GMC Sierra

  1. Faulty Exhaust Gas Temperature Sensor: The sensor itself may be malfunctioning, leading to high voltage readings.
  2. Damaged Wiring or Connectors: Corrosion or damage to the wiring or connectors connected to the sensor can cause high voltage issues.
  3. ECM Malfunction: A malfunctioning ECM can also send incorrect signals to the sensor, resulting in high voltage readings.
  4. Exhaust System Leak: A leak in the exhaust system can cause incorrect temperature readings, triggering this code.

Symptoms of P0546 2018 GMC Sierra

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Power: The vehicle may experience a decrease in power and acceleration due to incorrect fuel delivery.
  3. Poor Fuel Efficiency: High voltage readings from the exhaust gas temperature sensor can lead to poor fuel efficiency.
  4. Rough Idling: The engine may exhibit rough idling or misfires due to incorrect sensor readings.

How to Fix P0546 2018 GMC Sierra

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific code and perform testing to determine the root cause of the high voltage readings.
  2. Replace Exhaust Gas Temperature Sensor: If the sensor is faulty, replace it with a new one following manufacturer guidelines.
  3. Check Wiring and Connectors: Inspect the wiring and connectors for any damage or corrosion, repairing or replacing as necessary.
  4. Test ECM: Ensure the ECM is functioning correctly and reprogram if needed to address any issues with incorrect signals.
  5. Clear Codes and Test Drive: Clear the DTC from the ECM, and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P0546 2018 GMC Sierra

The typical repair costs for addressing a P0546 code on a 2018 GMC Sierra can range from $150 to $400, including parts and labor. However, it's important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Rates in metropolitan areas or at dealerships may be higher, while independent shops often charge less. It's advisable to check local rates for a more precise estimate.

What does this mean?

Tech Notes for P0546 2018 GMC Sierra

After starting the engine, the exhaust gas temperature sensor temperature should rise steadily, then stabilize after the engine reaches operating temperature. Exhaust gas temperature sensors may fail intermittently while operating under extreme temperatures. Review the Freeze Frame/Failure Records to verify the failure criteria.

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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 P0546 2018 GMC Sierra Code

1. What does the OBDII code P0546 mean on a 2018 GMC Sierra?

P0546 indicates a high voltage issue in the circuit for Exhaust Gas Temperature Sensor 1, which monitors the temperature of exhaust gases to optimize performance and emissions control.

2. What are the common symptoms of code P0546 on a 2018 GMC Sierra?

Symptoms may include a check engine light, reduced engine performance, poor fuel economy, excessive exhaust smoke, or the vehicle entering limp mode.

3. What causes the P0546 code to trigger on a 2018 GMC Sierra?

Common causes include a faulty exhaust gas temperature sensor, damaged wiring or connectors in the sensor circuit, or issues with the engine control module (ECM).

4. Can a dirty or clogged exhaust system cause the P0546 code?

While less common, a clogged exhaust system can cause excessive heat buildup, potentially damaging the sensor or its circuit and triggering the code.

5. How do you diagnose the P0546 code on a 2018 GMC Sierra?

Diagnosis typically involves using a scan tool to confirm the code, visually inspecting the wiring and connectors for damage, and testing the sensor's resistance and voltage output.

6. Can I drive my 2018 GMC Sierra with the P0546 code?

Driving is not recommended, as ignoring this code can lead to further damage to the exhaust system, reduced performance, and increased emissions.

7. How is the P0546 code fixed on a 2018 GMC Sierra?

Repairs may include replacing the faulty exhaust gas temperature sensor, repairing damaged wiring or connectors, or reprogramming the ECM if necessary.

8. How much does it cost to fix the P0546 code on a 2018 GMC Sierra?

Repair costs can range from $100 to $300, depending on whether the sensor needs replacement or if wiring repairs are required.

9. Can a software update fix the P0546 code on a 2018 GMC Sierra?

In rare cases, a software update to the ECM may resolve the issue if it’s related to incorrect sensor readings or calibration.

10. How can I prevent the P0546 code from occurring on my 2018 GMC Sierra?

Regular maintenance, ensuring the exhaust system is clean and intact, and addressing wiring issues promptly can help prevent this code from recurring.

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