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 for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
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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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Justin

17 years of experience
42 reviews
Justin
17 years of experience
Justin was awesome
2014 GMC SIERRA 1500 - CHECK ENGINE LIGHT IS ON - PHOENIX, ARIZONA

Jose

14 years of experience
433 reviews
Jose
14 years of experience
He did a awesome job!! The first guy who did the original testing was wrong. Jose figured the right problem out in no time. Thank you so much Jose. I will be definitely calling you next time!!
2005 SATURN ION - CHECK ENGINE LIGHT IS ON - PORTLAND, OREGON

Michael

24 years of experience
206 reviews
Michael
24 years of experience
2006 TOYOTA SOLARA - CHECK ENGINE LIGHT IS ON - TORRANCE, CALIFORNIA

Justin

13 years of experience
57 reviews
Justin
13 years of experience
Justin arrives a little late; however, he completed the diagnostic on a timely fashion. He thoroughly explained the code and what exactly needs to happen for the engine light to come off. He provided in depth summary, media, details and recommendation via email. The media was useful. He provided photos for the fault. The voice notes described reason for visit, problem found, and service provided. Justin completed a cost estimate for Your Mechanic to process.
2014 CHEVROLET SONIC - CHECK ENGINE LIGHT IS ON - ROSEVILLE, CALIFORNIA

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