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Engine-Codes – Generic – P25AF

P25AF Code - Coolant Temperature Control Module Requested MIL Illumination

Quick Answer

The P25AF diagnostic trouble code (DTC) stands for "Coolant Temperature Control Module Requested MIL Illumination." This code indicates that the coolant temperature control module has detected an issue that requires the malfunction indicator lamp (MIL), also known as the check engine light, to be illuminated on the vehicle's dashboard. Common causes include Faulty Coolant Temperature Sensor: A faulty coolant temperature sensor can send incorrect signals to the coolant temperature control module, triggering this code, Wiring Issues: Any damaged or corroded wiring connected to the coolant temperature control module can cause communication problems and result in this code being triggered, Coolant Temperature Control Module Failure: The coolant temperature control module itself may be faulty or malfunctioning, leading to the illumination of the MIL. 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 indicates Coolant Temperature Control Module Requested MIL Illumination.
Common causes
Common causes include Faulty Coolant Temperature Sensor: A faulty coolant temperature sensor can send incorrect signals to the coolant temperature control module, triggering this code, Wiring Issues: Any damaged or corroded wiring connected to the coolant temperature control module can cause communication problems and result in this code being triggered, Coolant Temperature Control Module Failure: The coolant temperature control module itself may be faulty or malfunctioning, leading to the illumination of the MIL.
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 Sep 12, 2024
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Code P25AF Description

The P25AF diagnostic trouble code (DTC) stands for "Coolant Temperature Control Module Requested MIL Illumination." This code indicates that the coolant temperature control module has detected an issue that requires the malfunction indicator lamp (MIL), also known as the check engine light, to be illuminated on the vehicle's dashboard. The coolant temperature control module is a vital component in the engine's cooling system, responsible for monitoring and regulating the temperature of the engine coolant to prevent overheating.

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

Common Causes of P25AF

  1. Faulty Coolant Temperature Sensor: A faulty coolant temperature sensor can send incorrect signals to the coolant temperature control module, triggering this code.
  2. Wiring Issues: Any damaged or corroded wiring connected to the coolant temperature control module can cause communication problems and result in this code being triggered.
  3. Coolant Temperature Control Module Failure: The coolant temperature control module itself may be faulty or malfunctioning, leading to the illumination of the MIL.
  4. Cooling System Problems: Issues with the cooling system, such as low coolant levels or a malfunctioning thermostat, can also trigger this code.
  5. Software or Calibration Issues: Sometimes, software glitches or calibration errors within the coolant temperature control module can cause it to request MIL illumination.

Symptoms of P25AF

  1. Illuminated Check Engine Light: The most obvious symptom of this code is the illumination of the check engine light on the dashboard.
  2. Engine Overheating: If the coolant temperature control module is not functioning correctly, it may lead to engine overheating.
  3. Poor Fuel Efficiency: A malfunctioning coolant temperature control module can also result in reduced fuel efficiency.
  4. Rough Idling: The engine may experience rough idling or misfires due to improper coolant temperature regulation.
  5. Engine Performance Issues: The vehicle may experience a decrease in performance or power output as a result of the coolant temperature control module malfunction.

How to Fix P25AF

  1. Diagnose the Issue: Begin by using a diagnostic tool to retrieve the DTC and identify the specific cause of the problem.
  2. Check Coolant Temperature Sensor: Test the coolant temperature sensor to ensure it is functioning correctly and replace if necessary.
  3. Inspect Wiring: Check the wiring harness connected to the coolant temperature control module for any damage or corrosion and repair or replace as needed.
  4. Replace Coolant Temperature Control Module: If the module itself is faulty, replace it with a new one to resolve the issue.
  5. Clear DTC and Reset MIL: Once the repair is completed, clear the DTC from the vehicle's system and reset the MIL to ensure the issue has been resolved.

Cost to Fix P25AF

The cost to repair a P25AF DTC can vary depending on the specific cause of the issue and the vehicle's make and model. In general, the cost of parts for this repair can range from $100 to $300, with labor costs adding an additional $100 to $200. Overall, the total repair cost for addressing this code typically falls between $200 and $500. It is essential to keep in mind that labor rates and diagnostic fees can vary between auto repair shops, so it is advisable to obtain quotes from local shops to get a more accurate estimate for your specific situation.

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Code P25AF Information for Specific Makes

  • P25AF Buick — Coolant Temperature Control Module Requested MIL Illumination
  • P25AF Cadillac — Coolant Temperature Control Module Requested MIL Illumination
  • P25AF Chevrolet — Coolant Temperature Control Module Requested MIL Illumination
  • P25AF GMC — Coolant Temperature Control Module Requested MIL Illumination
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 Code

1. What are the common symptoms of OBDII code P25AF?

- Common symptoms include the malfunction indicator lamp (MIL) or check engine light illuminating on the dashboard and potential issues with the coolant temperature control system.

2. What does the OBDII code P25AF indicate?

- The code P25AF indicates a problem with the Coolant Temperature Control Module Requested MIL Illumination, which is a module that controls the coolant temperature in the engine.

3. What are possible causes of OBDII code P25AF?

- Possible causes include a faulty coolant temperature control module, wiring issues, a defective engine coolant temperature sensor, or problems with the vehicle's computer system.

4. How serious is OBDII code P25AF?

- While the code itself may not indicate a critical issue with the vehicle's drivability, it is important to address it promptly to prevent potential damage to the engine or emissions system.

5. Can I continue driving with OBDII code P25AF?

- It is generally not recommended to continue driving with the code present, as unresolved issues with the coolant temperature control system can lead to overheating or other engine problems.

6. How can I diagnose and repair OBDII code P25AF?

- Diagnosis typically involves using a scan tool to read the code, checking the coolant temperature control module and related components for faults, and addressing any identified issues through repairs or replacements.

7. Will resetting the OBDII code P25AF make it go away permanently?

- Simply resetting the code may temporarily turn off the MIL light, but if the underlying issue is not addressed, the code is likely to reappear once the problem is detected again by the vehicle's system.

8. How much does it cost to fix OBDII code P25AF?

- Repair costs can vary depending on the specific cause of the code, the extent of the issue, and labor rates in your area. It is recommended to consult with a professional mechanic for an accurate estimate.

9. Can a DIY enthusiast fix OBDII code P25AF at home?

- Depending on your skill level and access to tools, some DIY enthusiasts may be able to diagnose and repair simple issues related to the code, but more complex problems may require professional assistance.

10. Is it necessary to pass an emissions test with OBDII code P25AF present?

- In most regions, vehicles with an illuminated MIL light will not pass an emissions test. It is important to address the code and ensure the vehicle is in proper working condition before attempting to pass any required tests.

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