P0879 Transmission Fluid Pressure Sensor/Switch D Circuit Intermittent

P0879 indicates an intermittent pressure sensor or switch D circuit fault. The D pressure signal drops out, spikes, or becomes invalid only sometimes.

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 clear intermittent pressure sensor D faults without reproducing the signal loss or instability.

Useful checks before replacing parts

Record pressure sensor D data during road vibration, hot operation, shift events, and harness movement to capture intermittent faults.
Inspect internal harness clips, case connector pins, fluid intrusion, terminal tension, sensor connector fit, and heat-sensitive opens.
Compare the intermittent pressure signal with pressure-control commands, gear ratio changes, slip events, and freeze-frame conditions.

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.