P0890TCM Power Relay Sense Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some gearboxes draw their power through a relay, such as the transmission control relay in Chrysler's fuse box that feeds the solenoids. P0885 to P0887 cover the coil control of that relay, P0888 to P0892 its sense line, which reads back the switched output and compares it with the command. A dead relay leaves all solenoids without power, so the gearbox drops into its hydraulic emergency gear. P0890 means the relay delivers no voltage despite the command. Subaru documents it in four bulletins from 2022 to 2025 (Ascent, WRX, Impreza, Crosstrek, Forester): after a short trip below 0 °C condensation freezes the ignition relay contacts, the starter does not crank and P0700 often comes along. Engine module software cycles the contacts; the 2025 Forester also gets a vented relay.
- What you may notice
- Starter does not crank after a short trip in frost (Subaru)
- MIL on, P0700 in the engine module
- False oil level or other warnings
- Likely causes
- LikelyRelay contacts frozen or corroded (Subaru ignition relay)
- LikelyOutdated engine module software (Subaru)
- PossibleFuse or wire between relay and gearbox module
- RareWeak battery
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Usually a job for a workshop.Typical cost: €30 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.