P0946 Hydraulic Pump Relay Circuit Range/Performance

P0946 indicates hydraulic pump relay circuit range/performance. The relay circuit may work electrically but pump power or pressure response is not as expected.

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 judge relay performance from a click test alone; verify loaded voltage and pressure response.

Symptoms of P0946

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 P0946

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 relay command, relay output voltage, pump current draw, pressure build time, pressure sensor data, and system voltage.
Inspect relay contacts, socket heat damage, fuse connections, wiring voltage drop, pump load, and hydraulic pressure unit condition.
Check whether performance faults appear during cold start, hot operation, repeated pump cycles, or low battery voltage.

Related OBD-II codes

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