Code Definition

P0816 — Downshift Switch Circuit

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

About P0816

P0816 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.

When P0816 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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 P0816 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

Fault code P0816 is set when the vehicle's powertrain control module (PCM) or transmission control module (TCM) detects a malfunction within the downshift switch circuit. This circuit is integral to the transmission control system in vehicles with manual transmissions or semi-automatic transmissions that allow manual gear selection. The downshift switch is used to signal the control modules when the driver initiates a shift to a lower gear. A fault in this circuit can lead to issues with the vehicle's ability to correctly register or execute downshift commands.

Quick Facts