Engine-CodesGeneric – P077B

P077B Code - Output Speed Sensor Circuit - Direction Error

Quick Answer

The P077B diagnostic trouble code (DTC) indicates a problem with the Output Speed Sensor Circuit, specifically a direction error. Common causes include Faulty output speed sensor, Damaged wiring or connectors in the sensor circuit, Issues with the transmission control module. 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
P077B indicates Output Speed Sensor Circuit - Direction Error.
Common causes
Common causes include Faulty output speed sensor, Damaged wiring or connectors in the sensor circuit, Issues with the transmission control module.
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 13, 2024
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Code P077B Description

The P077B diagnostic trouble code (DTC) indicates a problem with the Output Speed Sensor Circuit, specifically a direction error. The output speed sensor is responsible for monitoring the speed of the transmission output shaft. This information is crucial for the transmission control module to determine the appropriate shift points and ensure smooth operation of the transmission.

OBDII Code P077B - Output Speed Sensor Circuit - Direction Error
P077B Code - Output Speed Sensor Circuit - Direction Error

Common Causes of P077B

  1. Faulty output speed sensor
  2. Damaged wiring or connectors in the sensor circuit
  3. Issues with the transmission control module
  4. Low transmission fluid level
  5. Internal transmission damage

Symptoms of P077B

  1. Harsh or delayed shifting
  2. Erratic transmission behavior
  3. Transmission slipping
  4. Illumination of the Check Engine Light
  5. Reduced fuel efficiency

How to Fix P077B

  1. Begin by connecting a diagnostic scanner to the vehicle's onboard computer to retrieve the specific details of the P077B code.
  2. Inspect the output speed sensor and its wiring for any visible damage or corrosion. Replace the sensor if necessary.
  3. Check the transmission control module for any signs of malfunction and reprogram or replace it as needed.
  4. Ensure the transmission fluid level is at the correct level and top up if necessary.
  5. Clear the DTC and test drive the vehicle to confirm that the issue has been resolved.

Cost to Fix P077B

The typical repair costs for addressing a P077B code can vary depending on the specific cause of the issue. In general, replacing the output speed sensor can cost between $100 and $200, including parts and labor. If the issue is related to the transmission control module or internal transmission damage, the repair costs can increase significantly. It is advisable to consult with a professional mechanic to get an accurate estimate based on the specific circumstances of your vehicle. Keep in mind that labor rates at auto repair shops can vary, so it's recommended to check local rates for a more precise estimate.

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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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