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Engine-Codes – Generic – P0812

P0812 Code - Reverse Input Circuit

Quick Answer

The P0812 diagnostic trouble code refers to the Reverse Input Circuit in the vehicle's transmission system. Common causes include Faulty reverse input sensor, Wiring or connection issues in the reverse input circuit, Malfunctioning transmission control module (TCM). 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
P0812 indicates Reverse Input Circuit.
Common causes
Common causes include Faulty reverse input sensor, Wiring or connection issues in the reverse input circuit, Malfunctioning transmission control module (TCM).
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 Aug 19, 2024
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Code P0812 Description

The P0812 diagnostic trouble code refers to the Reverse Input Circuit in the vehicle's transmission system. This code indicates that there is a malfunction or fault in the circuit that controls the reverse gear engagement. In automatic transmissions, this circuit is responsible for detecting when the vehicle is shifted into reverse and sending the signal to engage the reverse gear. If this circuit is faulty, it can lead to issues with shifting into reverse or engaging reverse gear properly.

OBDII Code P0812 - Reverse Input Circuit
P0812 Code - Reverse Input Circuit

Common Causes of P0812

  1. Faulty reverse input sensor
  2. Wiring or connection issues in the reverse input circuit
  3. Malfunctioning transmission control module (TCM)
  4. Low transmission fluid level
  5. Mechanical issues within the transmission itself

Symptoms of P0812

  1. Difficulty shifting into reverse gear
  2. Delayed engagement of reverse gear
  3. Inability to engage reverse gear at all
  4. Harsh shifting when moving from park to reverse
  5. Transmission slipping while in reverse

How to Fix P0812

  1. Begin by conducting a thorough inspection of the reverse input circuit, including the sensor and wiring connections.
  2. Test the reverse input sensor for proper operation using a multimeter.
  3. Check the transmission control module for any fault codes and address any issues found.
  4. Inspect the transmission fluid level and condition, topping up or replacing as needed.
  5. If no issues are found with the sensor, wiring, TCM, or fluid level, further diagnostic testing may be required to pinpoint the exact cause of the circuit malfunction.

Cost to Fix P0812

The typical repair costs for addressing a P0812 code can vary depending on the specific cause of the issue. In general, expect to pay anywhere from $100 to $500 for parts and labor. Keep in mind that diagnostic time and labor rates can vary, so it's advisable to check with local auto repair shops for a more accurate estimate. Additionally, costs may be higher if the transmission control module needs to be replaced or if there are other underlying transmission issues that need to be addressed.

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Code P0812 Information for Specific Makes

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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