P0943 Hydraulic Pressure Unit Cycling Period Too Short

P0943 points to a hydraulic pressure unit cycling period that is too short. The system is rebuilding pressure too often or losing pressure too quickly.

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 pump alone if pressure loss, accumulator leakage, or sensor error is causing short cycling.

Symptoms of P0943

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 P0943

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 pressure unit cycling interval, pressure sensor data, pump command, hydraulic temperature, and actuator requests during operation.
Inspect for hydraulic leaks, accumulator problems, pressure loss, pump relay sticking, sensor drift, and fluid level or aeration issues.
Check whether frequent cycling appears after long soak, during repeated shifts, at high temperature, or with one actuator command.

Related OBD-II codes

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