AutoCodes – GMC – P242D 2018 GMC Sierra

P242D 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 3 Circuit High 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: P242D 2018 GMC Sierra indicates Exhaust Gas Temperature Sensor 3 Circuit High 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 277

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 P242D 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 greater than 900 Ω for greater than 2 s.

OBDII Code P242D 2018 GMC Sierra - Exhaust Gas Temperature Sensor 3 Circuit High Voltage - AutoCodes.com — P242D 2018 GMC Sierra Code - Exhaust Gas Temperature Sensor 3 Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P242D 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 P242D 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 P242D 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 P242D 2018 GMC Sierra code?

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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 P242D 2018 GMC Sierra Code

1. What does the OBDII code P242D mean on a 2018 GMC Sierra?

P242D indicates a high voltage issue in the Exhaust Gas Temperature (EGT) Sensor 3 circuit, typically located in the exhaust system downstream of the turbocharger or catalytic converter.

2. What are the common symptoms of code P242D in a 2018 GMC Sierra?

Symptoms include an illuminated check engine light, reduced fuel efficiency, poor engine performance, or the engine entering limp mode.

3. What causes the P242D code to appear on my 2018 GMC Sierra?

Possible causes include a faulty EGT sensor, damaged wiring or connectors, soot buildup on the sensor, or a malfunctioning Powertrain Control Module (PCM).

4. Can I drive my 2018 GMC Sierra with the P242D code?

While the truck may still be drivable, doing so can lead to further engine or emission system damage. Itâ€™s best to address the issue promptly.

5. How do I diagnose the P242D code on my 2018 GMC Sierra?

Start by inspecting the EGT sensor and its wiring for damage or corrosion. Use a multimeter to check the sensorâ€™s voltage and resistance, and scan for any additional related codes.

6. How can I fix the P242D code on a 2018 GMC Sierra?

Repairs may include replacing the EGT sensor, repairing or replacing damaged wiring, cleaning the sensor if itâ€™s clogged with soot, or updating/replacing the PCM if necessary.

7. How much does it cost to fix the P242D code on a 2018 GMC Sierra?

The cost varies. Replacing the EGT sensor typically costs $150-$400, while addressing wiring issues or PCM replacement may cost more depending on labor rates and parts.

8. What tools do I need to repair the P242D code on my 2018 GMC Sierra?

Youâ€™ll need an OBDII scanner, a multimeter, and potentially basic hand tools like a socket set for sensor replacement.

9. Can a dirty EGT sensor cause the P242D code?

Yes, soot or debris buildup on the sensor can interfere with its readings, potentially triggering the P242D code.

10. Does a software update fix the P242D code on a 2018 GMC Sierra?

In some cases, a PCM software update may resolve the issue if the problem is related to a known programming fault. Consult a dealership or qualified technician for confirmation.