P0891TCM Power Relay Sense Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- 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. P0891 means voltage is present at the relay output although the relay is off: a stuck or welded contact or a back-feed. The module then cannot switch the solenoids off for a safe emergency gear, and it may stay powered after key-off and drain the battery. No maker documents the code.
- What you may notice
- MIL on
- Battery drains overnight
- Module stays awake after key-off
- Likely causes
- LikelyRelay contact welded or sticking
- PossibleSense or output line shorted to voltage
- RareWrong relay fitted
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €20 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.