P0840 Transmission Fluid Pressure Sensor/Switch A Circuit

P0840 points to transmission fluid pressure sensor or switch A circuit. The controller detected a fault in the pressure feedback path.

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 clutches or valve-body parts before verifying the pressure sensor A circuit and actual pressure behavior.

Useful checks before replacing parts

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.