Engine-CodesGMC – P1812 GMC

P1812 GMC Code - Transmission Fluid Overtemperature

Quick Answer

The P1812 GMC code indicates that the transmission fluid in the vehicle has reached an overtemperature condition. Common causes include Low transmission fluid levels, Faulty transmission cooler or cooler lines, Blocked transmission cooler passages. 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
P1812 GMC indicates Transmission Fluid Overtemperature.
Common causes
Common causes include Low transmission fluid levels, Faulty transmission cooler or cooler lines, Blocked transmission cooler passages.
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.
Table of contents Created and updated by William Orellana on Sep 09, 2024
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Code P1812 GMC Description

The P1812 GMC code indicates that the transmission fluid in the vehicle has reached an overtemperature condition. This can occur when the transmission fluid becomes too hot, typically above the normal operating range. Transmission fluid plays a crucial role in the proper functioning of the transmission system, as it lubricates moving parts, transfers power, and helps to maintain optimal operating temperatures. When the transmission fluid overheats, it can lead to a range of issues that can affect the vehicle's performance and longevity.

OBDII Code P1812 GMC - Transmission Fluid Overtemperature
P1812 GMC Code - Transmission Fluid Overtemperature

Common Causes of P1812 GMC

  1. Low transmission fluid levels
  2. Faulty transmission cooler or cooler lines
  3. Blocked transmission cooler passages
  4. Malfunctioning transmission fluid pump
  5. Driving in extreme heat or heavy towing/hauling loads

Symptoms of P1812 GMC

  1. Rough shifting or hesitation when changing gears
  2. Transmission slipping
  3. Transmission overheating warning light illuminated on the dashboard
  4. Burning smell coming from the transmission area
  5. Transmission fluid leaks

How to Fix P1812 GMC

  1. Check transmission fluid levels and top up if low
  2. Inspect transmission cooler and lines for leaks or blockages
  3. Flush the transmission fluid and replace with fresh fluid
  4. Inspect and replace the transmission fluid pump if necessary
  5. Address any underlying issues causing the transmission to overheat, such as driving habits or towing practices

Cost to Fix P1812 GMC

The cost of repairing a transmission fluid overtemperature issue can vary depending on the specific cause of the problem. In general, replacing transmission fluid and performing a flush can cost between $100 and $250, including parts and labor. If additional repairs such as replacing the transmission fluid pump or cooler are necessary, the cost can increase significantly. It's important to consult with a professional mechanic to accurately diagnose the issue and provide an estimated cost for repairs. Keep in mind that labor rates and parts prices can vary, so it's advisable to get multiple quotes before proceeding with the repair.

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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.

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