P0850 Park/Neutral Switch Input Circuit

P0850 points to a park or neutral switch input circuit fault. The control module cannot trust the signal that identifies park or neutral state.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Transmission
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

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 park/neutral safety logic; diagnose the input circuit because it affects start safety.

Useful checks before replacing parts

Compare park/neutral switch data with actual shifter position, starter enable, range sensor data, and gear display behavior.
Inspect switch adjustment, linkage alignment, connector condition, power feed, ground, and wiring near the shifter or transmission.
Check for no-crank, crank-in-gear risk, shift interlock, reverse lamp, or range display symptoms that match the input fault.

Related OBD-II codes

These nearby transmission entries can help compare wording and fault area. They may share the same verification status as the source database.