AutoCodes – Generic – P251A

P251A 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 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 55,861

How popular is this code, among other codes? Medium

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
Comments
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Code P251A 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 - Power Take-Off Enable Switch Circuit - AutoCodes.com — P251A Code - Power Take-Off Enable Switch Circuit

What does this mean?

What are the Possible Causes of the DTC P251A?

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?

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 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.

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Information for Specific Makes

P251A Buick — Power Take-Off Enable Switch Circuit
P251A Cadillac — Power Take-Off Enable Switch Circuit
P251A Chevrolet — Power Take-Off Enable Switch Circuit
P251A Ford — Power Take-Off Enable Switch Circuit
P251A GMC — Power Take-Off Enable Switch Circuit

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.