AutoCodes – GMC – P257E GMC

P257E GMC 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 GMC 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 1,932

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 Aug 01, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P257E GMC 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 GMC - Engine Hood Switch Circuit Low Voltage - AutoCodes.com — P257E GMC Code - Engine Hood Switch Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P257E GMC?

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 GMC?

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 GMC 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 GMC code?

Need more information on how to fix the P257E GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific GMC Models

P257E 2014 GMC Sierra — Engine Hood Switch Circuit Low Voltage
P257E 2015 GMC Sierra — Engine Hood Switch Circuit Low Voltage
P257E 2016 GMC Sierra — Engine Hood Switch Circuit Low Voltage
P257E 2017 GMC Sierra — Engine Hood Switch Circuit Low Voltage
P257E 2018 GMC Sierra — Engine Hood Switch Circuit Low Voltage

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 GMC Code

1. What are common symptoms of OBDII code P257E GMC (Engine Hood Switch Circuit Low Voltage)?

The common symptoms include the hood open warning light being illuminated on the dashboard, difficulty starting the vehicle, and potential issues with the vehicle's remote start system.

2. What can cause the OBDII code P257E GMC to trigger?

The code P257E GMC is typically triggered by a faulty hood switch, damaged wiring in the hood switch circuit, or a malfunctioning body control module (BCM).

3. How can I diagnose the cause of OBDII code P257E GMC?

Diagnosing the issue involves visually inspecting the hood switch and its wiring for any damage, testing the switch for proper functionality, and using a scan tool to check the BCM for any related faults.

4. Are there any quick repair tips for OBDII code P257E GMC?

Quick repair tips include checking and cleaning the hood switch contacts, repairing any damaged wiring, and resetting the BCM by disconnecting the battery for a few minutes.

5. Can I continue driving with the OBDII code P257E GMC present?

It is generally not recommended to continue driving with the code present, as it may lead to issues with the vehicle's starting system or other related functions.

6. How serious is OBDII code P257E GMC (Engine Hood Switch Circuit Low Voltage)?

While the code itself may not cause immediate drivability issues, it can lead to inconvenience and potential problems with the vehicle's starting and security systems if left unresolved.

7. How much does it typically cost to repair OBDII code P257E GMC?

The cost of repairing the P257E GMC code can vary depending on the underlying cause, but it may range from a simple DIY fix to a few hundred dollars if professional diagnosis and parts replacement are required.

8. Can a DIY enthusiast fix OBDII code P257E GMC at home?

Yes, DIY enthusiasts with some automotive repair experience can attempt to fix the P257E GMC code by inspecting and repairing the hood switch and its wiring, following repair guides or manuals.

9. Will disconnecting the battery reset OBDII code P257E GMC?

Disconnecting the battery for a few minutes may reset the code temporarily, but if the underlying issue with the hood switch circuit is not fixed, the code is likely to reappear.

10. How long does it take to repair OBDII code P257E GMC?

The repair time for the P257E GMC code can vary based on the cause and complexity of the issue. Simple fixes like cleaning the hood switch contacts may take a short time, while more involved repairs could take a few hours or longer.