P0889
TCM Power Relay Sense Circuit Range/Performance
Transmission / TCM power supply
Generic OBD-II
Medium
What it means
P0889 means the transmission control module's power-relay sense circuit is reading a voltage outside its normal range — the module can't confirm it's getting stable power through the relay. The engine still starts and runs, but unreliable module power can lead to erratic shifting or a protective limp mode until the relay or its wiring is repaired.
Medium
Can I keep driving? May still drive, but unstable power to the transmission module can cause erratic shifting or limp mode, so fix it before you get stranded.
Common symptoms
What you'll notice
- Check-engine light on
- Erratic or delayed shifting
- Transmission stuck in gear or in limp mode
- Intermittent transmission faults tied to power interruptions
Common causes
Most likely first
- Faulty TCM power relayLikely
- Wiring or connector fault on the relay sense circuitCommon
- Loose or corroded connections / poor groundCommon
- Failed transmission control moduleLess often
- Related control-module or supply fault (least likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and check the TCM power relay and its fuse.
- Inspect the sense-circuit wiring and connectors for corrosion, looseness, or voltage drop.
- Compare the relay's sensed voltage in live data against the expected range.
- Replace the power relay if it's switching incorrectly; repair any wiring faults.
- If the supply is stable and correct, diagnose the TCM itself.
FAQ
Quick answers
Is it safe to drive with P0889?+
Cautiously — unstable module power can cause sudden shifting problems or limp mode, so have it diagnosed promptly.
Can I just clear P0889?+
It returns until the relay or its wiring is fixed, because the module keeps sensing an out-of-range supply.
Related codes
Often seen with P0889
Read & clear P0889 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX