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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.
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.
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.
Common causes for a P0790 are:
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.
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.
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.
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.
The most common repairs for a P0790 are as follows:
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.
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.