Skip the auto shop - Our mechanics make house calls

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

check engine light

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.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...


Related questions

Q: Car will crank, doesnt stay running

Hello and thanks for your question. Ground wires will not have a voltage on them. Preform a resistance check on all of the pins to the harness plug. There should be resistance for the computer, high resistance for the power,...

Q: Check engine light is on.. Its not running any differently and it starts normally..

You need to have the engine computer scanned to see what trouble code is stored. Not all codes will cause the engine to run bad or cause a noticeable problem. For instance, a trouble code could be triggered by a...

Q: KOEO test code 332

Hello there, A few different things can cause insufficient EGR flow. The most likely are: a stuck closed EGR valve a failed EGR valve solenoid faulty oxygen sensor low fuel pressure exhaust leak These can also...