Engine-CodesGeneric – P077A

P077A Code - Output Speed Sensor Circuit - Loss of Direction Signal

Quick Answer

The P077A diagnostic trouble code (DTC) indicates a problem with the output speed sensor circuit, specifically the loss of direction signal. Common causes include Faulty output speed sensor, Damaged wiring or connectors in the sensor circuit, Corrosion or debris affecting the sensor's operation. 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
P077A indicates Output Speed Sensor Circuit - Loss of Direction Signal.
Common causes
Common causes include Faulty output speed sensor, Damaged wiring or connectors in the sensor circuit, Corrosion or debris affecting the sensor's operation.
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 11, 2024
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Code P077A Description

The P077A diagnostic trouble code (DTC) indicates a problem with the output speed sensor circuit, specifically the loss of direction signal. The output speed sensor is a crucial component in the transmission system that monitors the speed of the output shaft. This information is used by the vehicle's onboard computer to control various functions, such as shifting gears, torque converter lockup, and overall transmission performance.

OBDII Code P077A - Output Speed Sensor Circuit - Loss of Direction Signal
P077A Code - Output Speed Sensor Circuit - Loss of Direction Signal

Common Causes of P077A

  1. Faulty output speed sensor
  2. Damaged wiring or connectors in the sensor circuit
  3. Corrosion or debris affecting the sensor's operation
  4. Issues with the vehicle's onboard computer or transmission control module
  5. Fluid contamination affecting sensor performance

Symptoms of P077A

  1. Rough or delayed shifting between gears
  2. Erratic or unpredictable transmission behavior
  3. Illuminated check engine light
  4. Reduced fuel efficiency
  5. Vehicle going into limp mode

How to Fix P077A

  1. Perform a diagnostic scan to confirm the P077A code and identify the specific cause of the issue
  2. Inspect the output speed sensor, wiring, and connectors for any damage or corrosion
  3. Replace the output speed sensor if it is found to be faulty
  4. Repair or replace any damaged wiring or connectors in the sensor circuit
  5. Clear the DTC and test drive the vehicle to ensure the issue has been resolved

Cost to Fix P077A

The cost of repairing a P077A code can vary depending on the specific cause of the issue and the labor rates at the auto repair shop. Generally, replacing the output speed sensor and addressing any related wiring or connector issues can cost anywhere from $150 to $500, including parts and labor. It's essential to factor in additional costs for diagnostic time and any other necessary repairs to ensure the problem is fully resolved. As labor rates can vary, it's advisable to check with local auto repair shops for a more accurate estimate based on your vehicle make and model.

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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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