AutoCodes – Generic – P0790

P0790 Code - Normal/Performance Switch Circuit Malfunction

Quick Answer

The Transmission Control Module (TCM) monitors the Normal/Performance Switch signal. Common causes include Faulty Normal/Performance Switch, Normal/Performance Switch harness is open or shorted, Normal/Performance Switch circuit poor electrical connection. 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: P0790 indicates Normal/Performance Switch Circuit Malfunction.
Common causes: Common causes include Faulty Normal/Performance Switch, Normal/Performance Switch harness is open or shorted, Normal/Performance Switch circuit poor electrical connection.
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.

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Code Popularity 16,887

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 08, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P0790 Description

The Transmission Control Module (TCM) monitors the Normal/Performance Switch signal. The TCM sets the OBDII code when the Normal/Performance Switch is not to factory specifications.

OBDII Code P0790 - Normal/Performance Switch Circuit Malfunction - AutoCodes.com — P0790 Code - Normal/Performance Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0790?

Faulty Normal/Performance Switch
Normal/Performance Switch harness is open or shorted
Normal/Performance Switch circuit poor electrical connection

How to Fix the DTC P0790?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0790 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P0790 code?

Need more information on how to fix the P0790 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0790 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P0790 Mercedes-Benz — Normal/Performance Switch Circuit Malfunction
P0790 Volkswagen — Normal/Performance Switch Circuit Malfunction

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 P0790 Code

1. What does the OBDII code P0790 mean?

P0790 indicates a malfunction in the normal/performance switch circuit, which controls the vehicle's driving mode selection between normal and performance settings.

2. What are the common symptoms of code P0790?

Symptoms may include the inability to switch between driving modes, reduced performance, poor fuel efficiency, and the illumination of the check engine light.

3. What causes the P0790 code to appear?

Common causes include a faulty mode switch, damaged or corroded wiring, a malfunctioning transmission control module (TCM), or a short circuit in the system.

4. Can I drive with the P0790 code active?

While the vehicle may still be drivable, it could be stuck in one driving mode and may experience reduced performance or efficiency. It's best to address the issue promptly.

5. How do I diagnose the P0790 code?

Diagnosis involves checking the normal/performance switch for proper operation, inspecting the wiring and connectors for damage or corrosion, and using a scan tool to test the TCM.

6. How do I fix the P0790 code?

Repairs may include replacing the mode switch, repairing or replacing damaged wiring, cleaning corroded connectors, or reprogramming or replacing the TCM if necessary.

7. How much does it cost to repair a P0790 code?

Repair costs vary depending on the cause. Replacing a mode switch may cost $50–$200, while TCM repairs or replacements can exceed $500.

8. Can a dead battery cause the P0790 code?

A weak or dead battery might cause electrical issues, which could trigger the code. Ensure the battery and charging system are in good condition.

9. Is the P0790 code specific to any vehicle make or model?

No, the P0790 code is a generic OBDII code and can appear on any vehicle equipped with a normal/performance mode switch, though the exact diagnosis and repair steps may vary by manufacturer.

10. Will clearing the code solve the problem?

Clearing the code without addressing the underlying issue will only temporarily turn off the check engine light. The code will likely return until the problem is resolved.