AutoCodes – GMC – P257E 2018 GMC Sierra

P257E 2018 GMC Sierra Code - Engine Hood Switch Circuit Low Voltage

Quick Answer

The Engine Control Module (ECM) applies 5 V to the hood ajar signal circuit and monitors the voltage to determine the position of the hood. Common causes include Faulty Hood Ajar Switch, Hood Ajar Switch harness is open or shorted, Hood Ajar Switch 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: P257E 2018 GMC Sierra indicates Engine Hood Switch Circuit Low Voltage.
Common causes: Common causes include Faulty Hood Ajar Switch, Hood Ajar Switch harness is open or shorted, Hood Ajar Switch 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 174

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 Sep 21, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P257E 2018 GMC Sierra Description

The Engine Control Module (ECM) applies 5 V to the hood ajar signal circuit and monitors the voltage to determine the position of the hood. The hood ajar switch contains a multiplexed resistor. This resistor will vary the voltage seen by the Engine Control Module by pulling down the applied voltage based on the position of the switch. The Diagnostic Trouble Code (DTC) will be set when the Engine Control Module detects a short to ground in the hood ajar signal input to the Engine Control Module.

OBDII Code P257E 2018 GMC Sierra - Engine Hood Switch Circuit Low Voltage - AutoCodes.com — P257E 2018 GMC Sierra Code - Engine Hood Switch Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P257E 2018 GMC Sierra?

Faulty Hood Ajar Switch
Hood Ajar Switch harness is open or shorted
Hood Ajar Switch circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P257E 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P257E 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 P257E 2018 GMC Sierra code?

Need more information on how to fix the P257E 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 P257E 2018 GMC Sierra Code

What does the OBDII code P257E mean for a 2018 GMC Sierra?

It indicates a problem with the Engine Hood Switch Circuit, specifically low voltage detected by the vehicle's control module.

What are the common symptoms of the P257E code in a 2018 GMC Sierra?

Symptoms may include the check engine light turning on and potential issues with remote start or security system functionality.

What causes the P257E code in a 2018 GMC Sierra?

Common causes include a faulty hood switch, damaged wiring or connectors in the hood switch circuit, or issues with the vehicleâ€™s control module.

Can the P257E code affect the vehicle's performance?

Generally, it does not affect engine performance but may impact features like remote start or security systems.

How can I diagnose the P257E code in a 2018 GMC Sierra?

Start by visually inspecting the hood switch and wiring for damage, check for corrosion on connectors, and use a multimeter to test for proper voltage in the circuit.

How do I fix the P257E code in a 2018 GMC Sierra?

Repairs may include replacing the hood switch, repairing or replacing damaged wiring, or cleaning corroded connectors in the circuit.

Can I clear the P257E code without repairing the issue?

Clearing the code without addressing the root cause may temporarily turn off the check engine light, but the code is likely to return.

How much does it cost to repair the P257E code on a 2018 GMC Sierra?

The repair cost can vary, but replacing a hood switch typically costs $50-$150, while wiring repairs may cost more depending on the extent of damage.

Is it safe to drive with the P257E code on a 2018 GMC Sierra?

Yes, driving is generally safe, but features like the remote start or security system may not function properly.

Can I prevent the P257E code from occurring in the future?

Regular maintenance, such as inspecting electrical components and keeping connectors clean and dry, can help prevent issues with the hood switch circuit.