P0852 Park/Neutral Switch Input Circuit High

P0852 points to a high signal in the park or neutral switch input circuit. The module sees an open, short-to-voltage, or above-range signal.

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 assume the transmission is in the wrong range until the high input circuit is tested.

Symptoms of P0852

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 P0852

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 park/neutral signal voltage, ground path, connector condition, open circuits, short-to-voltage faults, and switch adjustment.
Compare scan-tool park/neutral status with actual shifter position and starter interlock behavior in every range.
Inspect recent transmission, shifter, or harness work that could leave the input circuit misadjusted or disconnected.

Related OBD-II codes

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