P0787 Shift/Timing Solenoid Low

P0787 indicates the shift or timing solenoid circuit is low. The control module sees low voltage, low current, or a grounded circuit condition.

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 solenoid before checking for a grounded wire or missing feed voltage.

Symptoms of P0787

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 P0787

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 solenoid power feed, driver control, circuit voltage, resistance, connector condition, and short-to-ground possibilities.
Compare solenoid command with actual shift timing and gear ratio to confirm when the low condition affects operation.
Inspect internal harness routing, case connector pins, fluid contamination, and shared circuits for other solenoid faults.

Related OBD-II codes

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