AutoCodes – Generic – P256F

P256F Code - A/C Request 'B' Circuit Range/Performance

Quick Answer

The Powertrain Control Module (PCM) monitors the refrigerant pressure through the Air Condition (A/C) Pressure Sensor. Common causes include Low refrigerant, Too much refrigerant, Faulty Low Side Pressure Sensor. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: P256F indicates A/C Request 'B' Circuit Range/Performance.
Common causes: Common causes include Low refrigerant, Too much refrigerant, Faulty Low Side Pressure Sensor.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 3,818

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jan 18, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P256F Description

The Powertrain Control Module (PCM) monitors the refrigerant pressure through the Air Condition (A/C) Pressure Sensor. The PCM supplies a 5V reference and a low reference to the sensor. Changes in the A/C refrigerant pressure causes the sensor signal to the PCM to vary. When the pressure is high, the signal is high. When the pressure is low, the signal is low. The PCM sets the OBII code when the signal from the sensor is out of factory specifications.

OBDII Code P256F - A/C Request 'B' Circuit Range/Performance - AutoCodes.com — P256F Code - A/C Request 'B' Circuit Range/Performance

What does this mean?

What are the Possible Causes of the DTC P256F?

Low refrigerant
Too much refrigerant
Faulty Low Side Pressure Sensor
Low Side Pressure Sensor harness is open or shorted
Low Side Pressure Sensor circuit poor electrical connection

How to Fix the DTC P256F?

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 P256F 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 P256F code?

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Need Help with the Code?

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Information for Specific Makes

P256F Chevrolet — A/C Request 'B' Circuit Range/Performance
P256F Dodge — A/C Request 'B' Circuit Range/Performance
P256F Ford — A/C Request 'B' Circuit Range/Performance
P256F GMC — A/C Request 'B' Circuit Range/Performance
P256F Mercedes-Benz — A/C Request 'B' Circuit Range/Performance

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.