P0951 Auto Shift Manual Control Circuit Range/Performance

P0951 indicates auto shift manual control range/performance. The manual shift request signal exists but is implausible, inconsistent, or outside expected limits.

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 the transmission controller before checking switch values and wiring under actual operation.

Symptoms of P0951

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 P0951

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

Monitor manual control input values while operating every manual shift control and compare them with module mode and gear display data.
Inspect switch resistance or voltage ladder values, connector corrosion, spilled-liquid damage, wiring flex points, and ground stability.
Check whether the fault appears in one direction, one selector gate, after moisture exposure, or during repeated manual shifts.

Related OBD-II codes

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