P0948 Hydraulic Pump Relay Circuit High

P0948 indicates a high hydraulic pump relay circuit. The relay control or output path is open, shorted to voltage, or above 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 bypass the pump relay; diagnose the high circuit because uncontrolled pump operation can damage the system.

Symptoms of P0948

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 P0948

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

Check relay control voltage, relay output, ground integrity, open circuits, short-to-voltage faults, socket condition, and driver state.
Inspect relay contacts, fuse block terminals, pump connector, harness routing, water intrusion, and wiring disturbed during service.
Compare relay command with pump current and pressure rise to confirm whether the high circuit prevents pump operation.

Related OBD-II codes

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