P0815 Upshift Switch Circuit

P0815 indicates an upshift switch circuit fault. The manual upshift request input is missing, stuck, or electrically outside the expected range.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace transmission hardware for a manual shift complaint until the upshift switch input is proven valid.

Symptoms of P0815

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0815

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Compare upshift switch data with actual paddle, lever, or button operation and verify that each press changes module data cleanly.
Inspect switch contacts, clock spring or shifter wiring, connector fit, water intrusion, reference voltage, and ground path.
Check whether manual mode, gear display, downshift switch data, or shift inhibit symptoms appear with the fault.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.