AutoCodes – GMC – P2521 GMC

P2521 GMC Code - A/C Request 'A' Circuit High

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: P2521 GMC indicates A/C Request 'A' Circuit High.
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 1,310

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 17, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2521 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 P2521 GMC - A/C Request 'A' Circuit High - AutoCodes.com — P2521 GMC Code - A/C Request 'A' Circuit High

What does this mean?

What are the Possible Causes of the DTC P2521 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 P2521 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 P2521 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 P2521 GMC code?

Need more information on how to fix the P2521 GMC code? Get Access to Factory Service Manuals

Need Help with the 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 P2521 GMC Code

1. What are common symptoms of OBDII code P2521 in a GMC related to the A/C Request 'A' Circuit High?

- Common symptoms include the air conditioning system not turning on, the A/C compressor not engaging, and the A/C not cooling properly.

2. What are potential causes of OBDII code P2521 GMC A/C Request 'A' Circuit High?

- Possible causes may include a faulty A/C compressor clutch relay, a short or open circuit in the A/C request circuit, or a malfunctioning A/C control module.

3. How can I diagnose OBDII code P2521 in my GMC for the A/C Request 'A' Circuit High?

- Diagnosis typically involves checking the A/C compressor clutch relay, inspecting the wiring and connectors in the A/C request circuit, and testing the A/C control module for proper operation.

4. Can a DIYer repair OBDII code P2521 GMC A/C Request 'A' Circuit High?

- Repairing this code may require advanced electrical troubleshooting skills and specialized tools, so it is recommended to consult a professional mechanic for proper diagnosis and repair.

5. Is it safe to continue driving with OBDII code P2521 related to the A/C Request 'A' Circuit High?

- While driving with this code may not cause immediate harm to the vehicle, it is best to address the issue promptly to ensure proper function of the air conditioning system.

6. Are there any simple checks I can perform before taking my GMC in for OBDII code P2521 repair?

- You can start by checking the A/C compressor clutch relay and ensuring all related fuses are intact. Also, inspect the wiring for any visible damage or loose connections.

7. What is the typical cost to repair OBDII code P2521 in a GMC for the A/C Request 'A' Circuit High?

- The cost of repairs can vary depending on the exact cause of the issue, but expect to pay for diagnostic time, replacement parts, and labor, potentially ranging from $100 to $500 or more.

8. Can a bad A/C Request 'A' Circuit High affect other vehicle systems in a GMC?

- While the primary impact is on the air conditioning system, a malfunction in this circuit could potentially affect other electrical systems in the vehicle, so it is best to address the issue promptly.

9. Will resetting the OBDII code P2521 clear the issue related to the A/C Request 'A' Circuit High in my GMC?

- Resetting the code may temporarily turn off the check engine light, but it will not fix the underlying issue causing the A/C Request 'A' Circuit High problem.

10. How can I prevent OBDII code P2521 related to the A/C Request 'A' Circuit High from recurring in my GMC?

- To prevent recurrence, it is essential to ensure regular maintenance of the air conditioning system, address any electrical issues promptly, and follow proper diagnostic procedures in case of similar symptoms.