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Engine-Codes – GMC – P27F0 GMC

P27F0 GMC Code - Transmission Range Control Valve 2 Position Switch Performance

Quick Answer

The P27F0 code indicates a performance issue with the Transmission Range Control Valve 2 Position Switch, which plays a crucial role in the operation of the vehicle's transmission system. Common causes include Low transmission fluid levels affecting hydraulic pressure, Faulty Transmission Range Control Valve 2 Position Switch, Transmission Range Control Valve 2 Position Switch harness is open or shorted. 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
P27F0 GMC indicates Transmission Range Control Valve 2 Position Switch Performance.
Common causes
Common causes include Low transmission fluid levels affecting hydraulic pressure, Faulty Transmission Range Control Valve 2 Position Switch, Transmission Range Control Valve 2 Position Switch harness is open or shorted.
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 02, 2025
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Code P27F0 GMC Description

The P27F0 code indicates a performance issue with the Transmission Range Control Valve 2 Position Switch, which plays a crucial role in the operation of the vehicle's transmission system. This switch is responsible for relaying the position of the transmission range to the Transmission Control Module (TCM). The TCM uses this information, along with inputs from various sensors such as the automatic transmission input and output speed sensors and the throttle position sensor, to manage the shifting of gears effectively. When the TCM detects that the input from the Transmission Range Control Valve 2 Position Switch is outside of the expected parameters, it triggers the P27F0 code.
OBDII Code P27F0 GMC - Transmission Range Control Valve 2 Position Switch Performance
P27F0 GMC Code - Transmission Range Control Valve 2 Position Switch Performance

Common Causes of P27F0 GMC

  1. Low transmission fluid levels affecting hydraulic pressure
  2. Faulty Transmission Range Control Valve 2 Position Switch
  3. Transmission Range Control Valve 2 Position Switch harness is open or shorted
  4. Poor electrical connection in the Transmission Range Control Valve 2 Position Switch circuit
  5. Faulty Control Valve Solenoid Body impacting transmission operation

Symptoms of P27F0 GMC

  1. Engine Light ON (or Service Engine Soon Warning Light)
  2. Erratic or harsh shifting between gears
  3. Transmission slipping or failing to engage
  4. Reduced fuel efficiency
  5. Unusual noises coming from the transmission

How to Fix P27F0 GMC

  1. Perform a thorough inspection of the transmission fluid level and condition, and top off or replace as necessary.
  2. Test the Transmission Range Control Valve 2 Position Switch for proper functionality using a multimeter.
  3. Inspect the wiring harness and connectors for any signs of damage, corrosion, or loose connections.
  4. If the switch is faulty, replace it with a new part and ensure all connections are secure.
  5. Check the Control Valve Solenoid Body for faults and replace if necessary to restore proper transmission function.

Cost to Fix P27F0 GMC

The cost to diagnose and repair the P27F0 code typically ranges from $200 to $600, depending on the specific issue and the parts required. Labor costs can vary significantly, with most shops charging between $80 and $150 per hour. Dealerships may charge higher rates, while independent shops often offer more competitive pricing. The final cost will depend on the make and model of the vehicle, the complexity of the repair, and the local labor market.

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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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