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P187E Cadillac Code - Transmission Park Valve Position Sensor 1 Performance

Quick Answer

The P187E code indicates a problem with the Transmission Park Valve Position Sensor 1, which is responsible for monitoring the position of the park valve within the transmission system. Common causes include Low transmission fluid levels, Faulty Transmission Park Valve, Transmission Park Valve 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
P187E Cadillac indicates Transmission Park Valve Position Sensor 1 Performance.
Common causes
Common causes include Low transmission fluid levels, Faulty Transmission Park Valve, Transmission Park Valve 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 P187E Cadillac Description

The P187E code indicates a problem with the Transmission Park Valve Position Sensor 1, which is responsible for monitoring the position of the park valve within the transmission system. This sensor plays a crucial role in ensuring that the vehicle can properly engage and disengage from the park position. When the gear selector is in the Park (P) position, the transmission fluid is drawn into the pump through the fluid filter assembly from the transmission fluid pan. A malfunction in the park valve position sensor can lead to incorrect readings, which may prevent the transmission from properly engaging in park mode. This can result in the vehicle rolling away unintentionally, posing a significant safety risk.
OBDII Code P187E Cadillac - Transmission Park Valve Position Sensor 1 Performance
P187E Cadillac Code - Transmission Park Valve Position Sensor 1 Performance

Common Causes of P187E Cadillac

  1. Low transmission fluid levels
  2. Faulty Transmission Park Valve
  3. Transmission Park Valve harness is open or shorted
  4. Poor electrical connection in the Transmission Park Valve circuit
  5. Faulty Control Valve Solenoid Body

Symptoms of P187E Cadillac

  1. Engine Light ON (or Service Engine Soon Warning Light)
  2. Transmission may not engage in Park position
  3. Unusual shifting behavior or harsh shifts
  4. Vehicle rolls when in Park position
  5. Delayed engagement when shifting from Park to Drive or Reverse

How to Fix P187E Cadillac

  1. Check and refill the transmission fluid to the proper level.
  2. Inspect the Transmission Park Valve for any signs of damage or wear.
  3. Test the Transmission Park Valve harness for continuity and check for shorts or opens.
  4. Examine the electrical connections in the Transmission Park Valve circuit for corrosion or loose connections.
  5. Replace the Control Valve Solenoid Body if it is found to be faulty.

Cost to Fix P187E Cadillac

The cost to diagnose and repair a P187E code can vary significantly based on the specific issue and the vehicle make and model. Typically, you might expect to pay between $150 and $500 for parts and labor. The cost of parts, such as a new Transmission Park Valve or Control Valve Solenoid Body, can range from $50 to $300, while labor costs generally range from $80 to $150 per hour, depending on the shop and location. Dealerships may charge higher rates, while independent shops may offer more competitive pricing.

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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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