OBD-II Code P0790 — What It Means & How to Fix It

What Does This Error Mean?

P0790 means the Normal/Performance Switch Circuit has a malfunction. Some vehicles have a driver-selectable mode switch that changes transmission shift firmness and timing. When this switch or its circuit fails, the TCM cannot read the driver's mode preference. You may notice the transmission always shifts in one mode regardless of switch position. The check engine light will be on but driving is usually safe for short periods.

Affected Models

Vehicles with selectable Normal and Sport or Performance drive modes
Common in Chrysler, Dodge, and Jeep vehicles with 45RFE and 545RFE transmissions
Common in some Mitsubishi and Hyundai models with mode selector switches
Common in older GM vehicles with economy/performance switch circuits

Common Causes

Failed Normal/Performance mode selector switch with a broken internal contact
Open or short circuit in the wiring between the switch and the TCM
Corroded switch connector causing intermittent or no signal
Faulty TCM not reading the switch input signal correctly
Blown fuse in the switch circuit interrupting power to the switch

How to Fix It

Check for any related codes stored alongside P0790. TCM power or ground faults can cause false switch circuit codes.

Clear codes and retest first — P0790 occasionally sets as a temporary glitch if the switch is moved rapidly.
Locate the Normal/Performance switch. On most vehicles it is on the center console, dashboard, or gear selector area.

Consult your owner's manual if you are unsure where the mode switch is located.
Check the switch connector for corrosion, bent pins, or loose fit. Clean with electrical contact cleaner and reseat the connector.

Connector corrosion is a common cause on older vehicles or those driven in wet climates.
Test the switch with a multimeter. The switch should show continuity or a specific resistance value in each mode position. Replace if it does not.

Refer to the factory service manual for the exact resistance values expected in Normal and Performance positions.
Check wiring continuity between the switch and the TCM connector. Repair any broken or shorted wires found in the harness.

On Chrysler products, inspect the firewall wiring pass-through — this is a common chafe point.

When to Call a Professional

A switch replacement is usually $50 to $150 for the part. Wiring repair or connector cleaning adds $100 to $250 labor. If the TCM is at fault, TCM replacement and programming runs $300 to $700. This is generally a straightforward repair — most shops can handle it quickly.

Frequently Asked Questions

Will P0790 affect how my car drives?

Usually only mildly. The transmission will default to one shift mode and stay there. You lose the ability to switch between Normal and Performance modes. The car is generally safe to drive, but fix it soon.

Is the Normal/Performance switch expensive to replace?

Usually not — the switch itself is $50 to $150 on most vehicles. Labor is minimal since the switch is typically accessible from inside the cabin.

Can I ignore P0790 if the car shifts fine?

Short term, yes — it is not an immediate safety risk. However, leaving unresolved codes makes it harder to catch new issues. Fix it when convenient to keep your diagnostic system clean.