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Engine-Codes – GMC – P25AF GMC

P25AF GMC Code - Coolant Temperature Control Module Requested MIL Illumination

Quick Answer

The P25AF code indicates that the Coolant Temperature Control Module (CTCM) has requested the Malfunction Indicator Lamp (MIL) to be illuminated. Common causes include Faulty engine coolant temperature sensor (ECT), Malfunctioning Coolant Temperature Control Module (CTCM), Wiring issues, such as damaged or corroded connectors. 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
P25AF GMC indicates Coolant Temperature Control Module Requested MIL Illumination.
Common causes
Common causes include Faulty engine coolant temperature sensor (ECT), Malfunctioning Coolant Temperature Control Module (CTCM), Wiring issues, such as damaged or corroded connectors.
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.
What is this?
Table of contents Created and updated by William Orellana on Oct 06, 2024
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Code P25AF GMC Description

The P25AF code indicates that the Coolant Temperature Control Module (CTCM) has requested the Malfunction Indicator Lamp (MIL) to be illuminated. This code is specific to certain GMC vehicles and is associated with the engine's cooling system, which plays a crucial role in maintaining optimal engine temperature for performance and efficiency. The CTCM is responsible for monitoring the coolant temperature and ensuring that the engine operates within its designed temperature range. When the CTCM detects a fault or an abnormality in the coolant temperature readings, it triggers the MIL to alert the driver of a potential issue.

OBDII Code P25AF GMC - Coolant Temperature Control Module Requested MIL Illumination
P25AF GMC Code - Coolant Temperature Control Module Requested MIL Illumination

Common Causes of P25AF GMC

  1. Faulty engine coolant temperature sensor (ECT).
  2. Malfunctioning Coolant Temperature Control Module (CTCM).
  3. Wiring issues, such as damaged or corroded connectors.
  4. Low coolant levels or coolant leaks affecting temperature readings.
  5. Faulty thermostat that fails to regulate engine temperature properly.

Symptoms of P25AF GMC

  1. Illumination of the Malfunction Indicator Lamp (MIL) on the dashboard.
  2. Fluctuating engine temperature gauge readings.
  3. Overheating engine or excessive coolant temperature.
  4. Poor fuel economy or increased emissions.
  5. Engine performance issues, such as reduced power or stalling.

How to Fix P25AF GMC

  1. Diagnostic Testing: Begin by using an OBD-II scanner to confirm the P25AF code and check for any additional codes that may provide more context for the issue.
  2. Visual Inspection: Conduct a thorough visual inspection of the wiring and connectors associated with the ECT and CTCM for any signs of damage or corrosion.
  3. Sensor Testing: Test the engine coolant temperature sensor for proper resistance and functionality. Replace it if it is found to be faulty.
  4. CTCM Inspection: If the ECT is functioning correctly, inspect the CTCM for any signs of failure or malfunction. This may involve checking the module's programming and connections.
  5. Coolant System Check: Ensure that the coolant levels are adequate and check for leaks in the cooling system. Replace the thermostat if it is not functioning correctly.

Cost to Fix P25AF GMC

The cost to diagnose and repair a P25AF code can vary significantly based on the specific issue and the vehicle's make and model. On average, you can expect to pay between $150 and $500 for repairs, which may include parts and labor. Commonly, labor rates at auto repair shops range from $80 to $150 per hour. In metropolitan areas or at dealerships, rates may be higher, while independent shops might offer lower rates. The diagnostic time can also vary, typically taking 1 to 2 hours. It is advisable to check with local repair shops for a more precise estimate based on your specific vehicle and location.

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Information for Specific GMC Models

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 P25AF GMC Code

1. What are the common symptoms of OBDII code P25AF in a GMC vehicle?

Common symptoms include the check engine light illuminating, engine overheating, reduced engine performance, and potential coolant leaks.

2. What can cause the OBDII code P25AF to trigger in a GMC vehicle?

The code P25AF is typically triggered by a malfunction in the coolant temperature control module, which may be due to electrical issues, sensor failures, or software glitches.

3. How serious is the OBDII code P25AF in a GMC vehicle?

The code P25AF should be addressed promptly to prevent potential engine damage from overheating or coolant system failures. Ignoring the issue can lead to more costly repairs down the line.

4. What are some DIY repair tips for fixing the OBDII code P25AF in a GMC vehicle?

DIY repair tips may include checking for loose electrical connections, inspecting coolant levels and quality, and ensuring proper sensor functionality. However, it is recommended to consult a professional mechanic for an accurate diagnosis and repair.

5. Can driving with the OBDII code P25AF active in a GMC vehicle cause further damage?

Continuing to drive with the code P25AF active can lead to engine overheating, which may cause severe damage to engine components. It is advisable to address the issue as soon as possible.

6. How much does it typically cost to repair the OBDII code P25AF in a GMC vehicle?

The cost of repairing the OBDII code P25AF can vary depending on the extent of the issue, parts needed, and labor costs. It is recommended to get a few quotes from different mechanics to compare prices.

7. Is it safe to clear the OBDII code P25AF in a GMC vehicle without fixing the underlying issue?

Clearing the code without addressing the root cause may temporarily turn off the check engine light, but the problem will likely reoccur. It is essential to diagnose and repair the issue to prevent further complications.

8. Can extreme weather conditions affect the triggering of the OBDII code P25AF in a GMC vehicle?

Extreme weather conditions, such as very high or low temperatures, can potentially affect the performance of the coolant temperature control module and trigger the OBDII code P25AF. Proper maintenance is crucial in such conditions.

9. Will the OBDII code P25AF in a GMC vehicle cause a decrease in fuel efficiency?

Yes, the OBDII code P25AF can cause a decrease in fuel efficiency due to engine inefficiency resulting from coolant temperature control module malfunctions. Addressing the issue can help improve fuel economy.

10. How long does it typically take to repair the OBDII code P25AF in a GMC vehicle?

The repair time for the OBDII code P25AF can vary depending on the exact cause of the issue and the availability of parts. In most cases, the repair can be completed within a few hours to a day.

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