Engine-Codes.com
Engine-Codes – Generic – P0804

P0804 Code - 1-4 Upshift Skip Shift Lamp Control Circuit Malfunction

Quick Answer

The P0804 diagnostic trouble code (DTC) refers to a malfunction in the 1-4 upshift skip shift lamp control circuit. Common causes include Faulty skip shift lamp control circuit wiring, Defective skip shift lamp control module, Corroded or damaged electrical connectors. 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
P0804 indicates 1-4 Upshift Skip Shift Lamp Control Circuit Malfunction.
Common causes
Common causes include Faulty skip shift lamp control circuit wiring, Defective skip shift lamp control module, Corroded or damaged electrical connectors.
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 09, 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 P0804 Description

The P0804 diagnostic trouble code (DTC) refers to a malfunction in the 1-4 upshift skip shift lamp control circuit. This code is commonly found in vehicles with manual transmissions that are equipped with a skip shift feature. The skip shift system is designed to force the transmission to shift from first gear to fourth gear under certain conditions, such as low-speed driving, in order to improve fuel efficiency and reduce emissions. The skip shift lamp control circuit is responsible for illuminating a light on the dashboard to notify the driver when the skip shift feature is active.

OBDII Code P0804 - 1-4 Upshift Skip Shift Lamp Control Circuit Malfunction
P0804 Code - 1-4 Upshift Skip Shift Lamp Control Circuit Malfunction

Common Causes of P0804

  1. Faulty skip shift lamp control circuit wiring
  2. Defective skip shift lamp control module
  3. Corroded or damaged electrical connectors
  4. Failed engine control module (ECM) or transmission control module (TCM)
  5. Issues with the skip shift switch or sensor

Symptoms of P0804

  1. Check engine light illuminated on the dashboard
  2. Skip shift feature not engaging as expected
  3. Difficulty shifting gears, especially from first to fourth gear
  4. Decreased fuel efficiency
  5. Increased emissions output

How to Fix P0804

  1. Perform a thorough inspection of the skip shift lamp control circuit, including wiring and connectors, to identify any visible damage or corrosion.
  2. Test the skip shift lamp control module and related components for proper functionality using a multimeter or diagnostic tool.
  3. Replace any faulty components such as wiring, connectors, or the control module as needed.
  4. Clear the DTC from the vehicle's ECM/TCM memory and test drive the vehicle to ensure the skip shift feature is working correctly.
  5. If the issue persists, further diagnostics may be required to pinpoint the exact cause of the malfunction, potentially involving more in-depth electrical testing or module reprogramming.

Cost to Fix P0804

The cost of repairing a P0804 DTC can vary depending on the specific cause of the issue and the labor rates of the repair shop. On average, the cost of diagnosing and repairing a circuit malfunction like this could range from $100 to $300, including parts and labor. Keep in mind that rates can vary based on location, vehicle make and model, and the extent of the repair needed. It's recommended to consult with a professional mechanic for a more accurate cost estimate.

Need more information about the P0804 code?

Need more information on how to fix the P0804 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0804 code diagnosed by a professional: Find a repair shop in your area

Code P0804 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 P0804 Code

No Frequently Asked Questions about P0804 Code found.

Discuss the causes and fixes for P0804 OBDII Code

Submit a New Comment

Code P0804 comments

No comments found for this page.