P0790 OBD-II Trouble Code: Normal/Performance Switch Malfunction

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Cost of diagnosing the P0790 code

P0790 is a diagnostic trouble code (DTC) for "Normal/Performance Switch Malfunction". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P0790 trouble code definition

A P0790 trouble code is related to a vehicle’s automatic transmission and the normal/performance switch that changes the shift points for two different driving styles.

What the P0790 code means

P0790 is an OBD-II generic powertrain code for a voltage or resistance problem with the transmission mode controller in that the signal being sent out is not within the manufacturer’s parameters. This will typically not allow the powertrain control module to allow the “power mode” that usually lets the transmission shift later and downshift earlier.

What causes the P0790 code?

Common causes for a P0790 are:

  • Faulty transmission mode switch
  • Faulty switch wiring and or connectors

What are the symptoms of the P0790 code?

A P0790 can either cause a vehicle to stay in normal mode, or the transmission could fall into “limp-mode” that limits speeds so a vehicle can make it to a repair shop with minimal damage. The overdrive light may also be illuminated.

How does a mechanic diagnose the P0790 code?

A visual inspection of the transmission mode switch will be first, paying close attention to corrosion or liquid intrusion. If wiring appears damaged, it will need to be replaced. Your mechanic will be able to test the normal/power switch itself to determine if it’s functioning properly. If not, it will need to be replaced.

Common mistakes when diagnosing the P0790 code

Some mechanics have reported finding switches that are not so much damaged as corroded. These can be cleaned and replaced but it’s not a wise fix.

How serious is the P0790 code?

It’s rare for a P0790 to cause any symptoms more serious than the inability to access the transmission’s “power mode,” so this code isn’t too serious. If a vehicle does enter limp mode however, it can be more problematic.

What repairs can fix the P0790 code?

The most common repairs for a P0790 are as follows:

  • Cleaning the transmission mode switch
  • Replacing the transmission mode switch
  • Repairing damaged wiring for the transmission mode switch

Additional comments for consideration regarding the P0790 code

Some transmission mode switches are literally a console switch that says “Normal/Power” while others are activated when the transmission is switched to sport or dynamic mode.

Need help with a P0790 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

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Al

21 years of experience
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Al
21 years of experience
Nissan Pathfinder - Check Engine Light is on - Atlanta, Georgia
Al, was cool and very knowledgeable. Being direct and upfront always works. Al, is a credit to the company.

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10 years of experience
Chevrolet Equinox - Check Engine Light is on - Frisco, Texas
Xavier was GREAT!!! He made sure that I understood everything that he did to my vehicle and answered all my questions. Very thorough and even worked thru the light rain that we had. When I have to use this service again, I hope to be able to request him!

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14 years of experience
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Luis
14 years of experience
Kia Sorento - Check Engine Light is on - Las Vegas, Nevada
Luis did an excellent job in determining that this was a warranty issue on bad parts. He has integrity and is good at what he does. I would highly recommend him for any auto repairs that come up.

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Reginald
36 years of experience
BMW 325i - Check Engine Light is on - Los Angeles, California
Reginald was incredibly helpful in helping me to diagnose several issues in my car, as well as repair issues to help me pass a break and light test. He even went so far as to come to the brake and light testing location so that he could ensure that the car passed and be there if anything else needed to be fixed on the spot. Absolutely would recommend him to anyone who is looking for an honest and knowledgeable mechanic!


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