P0890 TCM Power Relay Sense Circuit Low

P0890 indicates a low TCM power relay sense circuit signal. The relay feedback voltage is lower than expected.

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 chase transmission shift faults until the low relay sense signal and TCM power feed are corrected.

Symptoms of P0890

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 P0890

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

Check relay output voltage, sense circuit continuity, fuse feed, relay socket condition, TCM connector pins, and grounds.
Compare relay command with actual sense voltage during key-on, cranking, and running states.
Inspect for corrosion, water intrusion, high resistance, or poor terminal tension in the relay and TCM power path.

Related OBD-II codes

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