P0904 Gate Select Position Circuit

P0904 indicates a gate select position circuit fault. The controller cannot reliably determine the selected gate position in the shift mechanism.

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 adjust actuators blindly before confirming gate position sensor data and linkage alignment.

Useful checks before replacing parts

Monitor gate select position data while moving through all gates and compare it with actual shifter or actuator movement.
Inspect position sensor reference voltage, signal, ground, connector fit, linkage alignment, actuator travel, and harness movement.
Check for companion gear shift position, actuator, or control error codes that show whether position data or motion is failing.

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.