AutoCodes – GMC – P242C 2018 GMC Sierra

P242C 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 3 Circuit Low Voltage

Quick Answer

The Exhaust Gas Temperature sensors (EGTS) are variable resistors that measure the temperature of the exhaust gas. Common causes include Faulty Exhaust Gas Temperature Sensor (EGTS) 3, Exhaust Gas Temperature Sensor 3 harness is open or shorted, Exhaust Gas Temperature Sensor 3 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: P242C 2018 GMC Sierra indicates Exhaust Gas Temperature Sensor 3 Circuit Low Voltage.
Common causes: Common causes include Faulty Exhaust Gas Temperature Sensor (EGTS) 3, Exhaust Gas Temperature Sensor 3 harness is open or shorted, Exhaust Gas Temperature Sensor 3 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 155

How popular is this code, among other codes? Low

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, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P242C 2018 GMC Sierra Description

The Exhaust Gas Temperature sensors (EGTS) are variable resistors that measure the temperature of the exhaust gas. Exhaust temperature sensor 1 is the first exhaust temperature sensor in the exhaust system, the following exhaust temperature sensors are counted upward from the engine outlet to the exhaust system end. The Engine Control Module (ECM) supplies 5 V to the exhaust gas temperature signal circuit and supplies a ground to the low reference circuit. The exhaust gas temperature sensor temperature information is used by the ECM during the exhaust gas particulate filter cleaning process. The Diagnostic Trouble Code (DTC) will ve set when the ECM detects that the exhaust gas temperature sensor is less than 158 Ω for greater than 2 s.

OBDII Code P242C 2018 GMC Sierra - Exhaust Gas Temperature Sensor 3 Circuit Low Voltage - AutoCodes.com — P242C 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 3 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P242C 2018 GMC Sierra?

Faulty Exhaust Gas Temperature Sensor (EGTS) 3
Exhaust Gas Temperature Sensor 3 harness is open or shorted
Exhaust Gas Temperature Sensor 3 circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P242C 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.

What does this mean?

Code Tech Notes

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.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P242C 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 P242C 2018 GMC Sierra code?

Need more information on how to fix the P242C 2018 GMC Sierra code? Get Access to Factory Service Manuals

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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 P242C 2018 GMC Sierra Code

1. What does the OBDII code P242C mean on a 2018 GMC Sierra?

P242C indicates that the powertrain control module (PCM) has detected a low voltage signal from Exhaust Gas Temperature Sensor 3, which monitors exhaust temperatures to optimize emissions and engine performance.

2. What are the common symptoms of the P242C code on a 2018 GMC Sierra?

Symptoms may include the check engine light turning on, decreased fuel efficiency, poor engine performance, and in some cases, the vehicle entering limp mode.

3. What causes the P242C code to appear on a 2018 GMC Sierra?

Common causes include a faulty exhaust gas temperature sensor, damaged wiring or connectors, excessive soot buildup on the sensor, or issues with the PCM.

4. Can I drive my 2018 GMC Sierra with the P242C code?

While the vehicle may still be drivable, continuing to drive with this code could lead to increased emissions, engine performance issues, or potential damage to the exhaust system.

5. How is the P242C code diagnosed on a 2018 GMC Sierra?

A technician will use an OBDII scanner to confirm the code, inspect the exhaust gas temperature sensor and its wiring for damage, and test the sensor's voltage output to determine if itâ€™s functioning correctly.

6. How do I fix the P242C code on a 2018 GMC Sierra?

Repairs may include replacing the faulty exhaust gas temperature sensor, repairing or replacing damaged wiring, cleaning soot buildup from the sensor, or updating/reprogramming the PCM if needed.

7. How much does it cost to repair the P242C code on a 2018 GMC Sierra?

The cost can vary depending on the issue, but replacing an exhaust gas temperature sensor typically ranges from $100 to $300, including parts and labor.

8. What tools are needed to repair the P242C code on a 2018 GMC Sierra?

Common tools include an OBDII scanner, multimeter for testing voltage, and basic hand tools for sensor removal and installation.

9. Can a dirty exhaust gas temperature sensor cause the P242C code?

Yes, excessive soot or carbon buildup on the sensor can interfere with its operation and trigger the code.

10. Is it necessary to clear the P242C code after repairs?

Yes, after repairs are completed, the code should be cleared using an OBDII scanner, and the vehicle should be test-driven to ensure the issue is resolved.