Code Definition

P0790 — Transmission mode switch signal error

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0790

P0790 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0790 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The fault code P0790 is set when the transmission control module (TCM) or the engine control module (ECM) in vehicles with integrated control systems detects an error in the signal from the transmission mode switch. This switch is responsible for communicating the driver's selected transmission mode (such as normal, sport, or manual mode) to the TCM/ECM. A signal error indicates that the switch is not providing correct or consistent information to the control modules, which can lead to issues in transmission behaviour as the system may not accurately understand the desired operational mode. Th...

Join TaT to view the complete code information and diagnostic details.

Quick Facts