AutoCodes – GMC – P251A 2018 GMC Sierra

P251A 2018 GMC Sierra Code - Power Take-Off Enable Switch Circuit

Quick Answer

The Power Take-Off (PTO) is an upfitter integrated system that allows the user to create an auxiliary power source. Common causes include Faulty Power Take Off (PTO) Enable Switch, Power Take Off Enable Switch harness is open or shorted, Power Take Off Enable 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: P251A 2018 GMC Sierra indicates Power Take-Off Enable Switch Circuit.
Common causes: Common causes include Faulty Power Take Off (PTO) Enable Switch, Power Take Off Enable Switch harness is open or shorted, Power Take Off Enable 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 163

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 P251A 2018 GMC Sierra Description

The Power Take-Off (PTO) is an upfitter integrated system that allows the user to create an auxiliary power source. The PTO system specifically controls engine speed to values higher than normal base idle, PTO load relay engagement, and remote starting and shutdown of the engine. When the operator requests PTO using either the PTO switch or PTO remote, the engine RPM will increase to a default standby speed. The Engine Control Module (ECM) converts the data from the engine speed sensor to a 2 pulses/engine revolution signal. When PTO is engaged, the power take-off control module sends a serial data message to the ECM requesting engine speeds, in response to signals from the PTO switch or remote.
The Diagnostic Trouble Code (DTC) will be set when the Power Take-Off Control Module detects a fault on the PTO enable switch circuit that is above or below a predetermined voltage threshold.

OBDII Code P251A 2018 GMC Sierra - Power Take-Off Enable Switch Circuit - AutoCodes.com — P251A 2018 GMC Sierra Code - Power Take-Off Enable Switch Circuit

What does this mean?

What are the Possible Causes of the DTC P251A 2018 GMC Sierra?

Faulty Power Take Off (PTO) Enable Switch
Power Take Off Enable Switch harness is open or shorted
Power Take Off Enable Switch circuit poor electrical connection
Faulty Power Take-Off Control Module

How to Fix the DTC P251A 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 P251A 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 P251A 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 P251A 2018 GMC Sierra Code

What does the OBDII code P251A mean on a 2018 GMC Sierra?

The code P251A indicates an issue with the Power Take-Off (PTO) Enable Switch Circuit, which controls the PTO system used for auxiliary equipment.

What are common symptoms of the P251A code in a 2018 GMC Sierra?

Symptoms include the PTO system not engaging, an illuminated check engine light, or reduced functionality of auxiliary equipment.

What causes the P251A code to appear on a 2018 GMC Sierra?

Common causes include a faulty PTO enable switch, damaged wiring or connectors in the PTO circuit, or a malfunctioning control module.

How do I diagnose a P251A code on a 2018 GMC Sierra?

Start by inspecting the PTO enable switch, wiring, and connectors for damage or corrosion. Use a scan tool to monitor PTO switch operation and check for related faults.

Can I drive my 2018 GMC Sierra with a P251A code?

Yes, you can drive the vehicle, but the PTO system may not function properly, potentially affecting any equipment reliant on it.

How do I fix the P251A code on my 2018 GMC Sierra?

Repairs may include replacing the PTO enable switch, repairing damaged wiring or connectors, or reprogramming or replacing the control module.

How much does it cost to fix a P251A code on a 2018 GMC Sierra?

Repair costs vary but typically range from $100 to $300 for parts and labor, depending on whether the issue is with the switch, wiring, or module.

Can a dead battery cause the P251A code on a 2018 GMC Sierra?

A dead or weak battery is unlikely to directly cause this code, but electrical issues from low voltage could contribute to circuit malfunctions.

What tools are needed to troubleshoot the P251A code in a 2018 GMC Sierra?

Youâ€™ll typically need a scan tool capable of reading live data, a multimeter to test electrical continuity, and basic hand tools for inspection and repairs.

Does the P251A code require professional repair on a 2018 GMC Sierra?

While DIY repairs are possible for simple issues like a faulty switch, complex wiring or module problems may require professional diagnosis and repair.