AutoCodes – GMC – P256F GMC

P256F GMC 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 GMC 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 1,020

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

What does this mean?

What are the Possible Causes of the DTC P256F GMC?

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 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 P256F 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 P256F GMC 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 P256F GMC Code

1. What are common symptoms of OBDII code P256F GMC?

- Common symptoms include the air conditioning system not functioning properly, reduced cooling performance, and the A/C not responding to commands.

2. What does the A/C Request 'B' Circuit Range/Performance error code (P256F) indicate in a GMC vehicle?

- This code indicates that there is an issue with the A/C request 'B' circuit, specifically regarding the range or performance of the circuit.

3. What are some possible causes of OBDII code P256F in a GMC vehicle?

- Possible causes include a faulty A/C compressor, wiring issues in the A/C system, a defective A/C control module, or a problem with the A/C pressure sensor.

4. How can I diagnose the A/C Request 'B' Circuit Range/Performance error code (P256F) in my GMC vehicle?

- Diagnosing this code may involve checking the A/C system components for proper operation, inspecting the wiring for any damage, and using a diagnostic tool to read live data from the A/C control module.

5. Can I continue to drive my GMC vehicle with OBDII code P256F present?

- It is not recommended to continue driving with this code present, as it can lead to further damage to the A/C system and potentially affect the overall performance of the vehicle.

6. What are some repair tips for fixing OBDII code P256F in a GMC vehicle?

- Repair tips may include checking and repairing any damaged wiring, replacing the A/C compressor or control module if necessary, and ensuring all A/C system components are functioning correctly.

7. How much does it typically cost to repair OBDII code P256F in a GMC vehicle?

- The cost of repair can vary depending on the specific issue causing the code, but it may range from a few hundred to over a thousand dollars, including parts and labor.

8. Can I reset the OBDII code P256F in my GMC vehicle by disconnecting the battery?

- While disconnecting the battery may temporarily clear the code, it is not a recommended method for resolving the underlying issue causing the A/C Request 'B' Circuit Range/Performance error.

9. How long does it take to repair OBDII code P256F in a GMC vehicle?

- The repair time can vary depending on the exact cause of the code and the complexity of the repair, but it may take a few hours to a full day to complete the necessary repairs.

10. Is it possible to prevent OBDII code P256F from occurring in my GMC vehicle?

- Regular maintenance of the A/C system, prompt repairs of any A/C-related issues, and keeping the system clean and free of debris can help prevent the occurrence of this error code.