Engine-Codes.com
Engine-Codes – Generic – P1871

P1871 Code - Undefined Gear Ratio

Quick Answer

The P1871 code indicates an undefined gear ratio in the vehicle's transmission. Common causes include Worn gear teeth, Malfunctioning shift solenoid, Low transmission fluid levels. 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
P1871 indicates Undefined Gear Ratio.
Common causes
Common causes include Worn gear teeth, Malfunctioning shift solenoid, Low transmission fluid levels.
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 Sep 07, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P1871 Description

The P1871 code indicates an undefined gear ratio in the vehicle's transmission. This means that the Engine Control Module (ECM) has detected that the transmission is not shifting correctly and the gear ratio is not within the expected parameters. This issue can lead to poor vehicle performance, transmission slipping, harsh shifting, and even transmission failure if not addressed promptly.

OBDII Code P1871 - Undefined Gear Ratio
P1871 Code - Undefined Gear Ratio

Common Causes of P1871

  1. Worn gear teeth
  2. Malfunctioning shift solenoid
  3. Low transmission fluid levels
  4. Faulty transmission control module
  5. Electrical issues within the transmission system

Symptoms of P1871

  1. Rough or harsh shifting between gears
  2. Slipping transmission
  3. Delayed engagement when shifting
  4. Decreased fuel efficiency
  5. Illumination of the Check Engine Light

How to Fix P1871

  1. Perform a diagnostic scan to confirm the P1871 code and identify the root cause of the issue.
  2. Check the transmission fluid level and quality, and top up or replace as necessary.
  3. Inspect the transmission for any visible damage or wear on gear teeth.
  4. Test and potentially replace the shift solenoid or transmission control module if found to be faulty.
  5. Clear the code from the ECM and test drive the vehicle to ensure the issue has been resolved.

Cost to Fix P1871

The cost of repairing a P1871 code can vary depending on the specific cause of the issue and the extent of the repairs needed. On average, the repair costs for this type of transmission issue can range from $200 to $1000, including parts and labor. It's important to note that the actual cost can be higher if major transmission components need to be replaced or if there are additional underlying issues that need to be addressed. Additionally, the diagnosis time and labor rates at auto repair shops can vary, so it's recommended to get a few quotes from different shops to compare prices.

Need more information about the P1871 code?

Need more information on how to fix the P1871 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1871 code diagnosed by a professional: Find a repair shop in your area

Code P1871 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.

Frequently Asked Questions about P1871 Code

No Frequently Asked Questions about P1871 Code found.

Discuss the causes and fixes for P1871 OBDII Code

Submit a New Comment

Code P1871 comments

No comments found for this page.