P0889 TCM Power Relay Sense Circuit Range/Performance

P0889 indicates range or performance trouble in the TCM power relay sense circuit. Relay feedback does not match the expected command or voltage behavior.

Code details

Generic OBD-II · P0

System: Transmission
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

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 assume the transmission has a hydraulic fault if relay sense is unstable; module power feedback must be fixed first.

Symptoms of P0889

Harsh, delayed, or slipping shifts, or being stuck in one gear.
Check-engine light, sometimes with limp-home mode.
Flaring RPM or a shudder under load.

Common causes of P0889

Low or degraded transmission fluid.
A failing speed sensor, shift solenoid, or pressure-control circuit.
Wiring, connector, or internal hydraulic/mechanical faults.

Useful checks before replacing parts

Monitor relay command, relay output, and sense voltage while cycling key states and loading the electrical system.
Inspect relay contacts, relay socket, sense wire, fuse feed, TCM connector condition, and ground path.
Check for intermittent voltage drops that occur during cranking, heat, vibration, or road-load conditions.

Related OBD-II codes

These nearby transmission entries can help compare wording and pin down the fault area.