P0921 Gear Shift Forward Actuator Circuit Range/Performance

P0921 points to gear shift forward actuator range/performance. Forward actuator movement or feedback is outside expected limits.

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 replace the actuator before checking mechanical drag and learned position limits.

Useful checks before replacing parts

Compare forward actuator command, current draw, travel feedback, learned limits, gear position data, and shift completion timing.
Inspect actuator binding, linkage adjustment, voltage drop, connector condition, mechanical drag, and adaptation or calibration requirements.
Check whether the fault appears in one gear, during hot operation, after service, or under fast shift requests.

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.