Error code

OBD2 P0891

OBD2P0891
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

TCM Power Relay Sense Circuit High.

Severity

moderateCan drive but transmission may be limited to 'limp mode'.

Summary

P0891 indicates an issue with the transmission control module (TCM) power relay sense circuit having abnormally high voltage.

Symptoms

  • Stored trouble code and illuminated warning light
  • Transmission may be held in a failsafe or 'limp mode'
  • Additional codes relating to system voltages may be present

Common Causes

  • Damaged, shorted, disconnected, or corroded wiring causing open circuits
  • Low battery voltage
  • Defective shift solenoid control relay
  • Failed or failing PCM/TCM (rare)

Diagnosis

  1. Check battery voltage and condition, clean terminals if necessary.
  2. Inspect relay feedback signal wire for continuity and resistance.
  3. Test relay input circuit for fuses or fusible links.
  4. Perform resistance tests on the shift solenoid control relay.

Fixes

  • Replace damaged wiring or corroded connections.
  • Check and clean battery terminals, ensure full voltage flow.
  • Replace defective shift solenoid control relay with OEM part.

FAQ

What does P0891 mean?

P0891 indicates an abnormally high voltage in the TCM power relay sense circuit.

How do I fix P0891?

Fixes include checking and cleaning battery terminals, inspecting wiring for damage or corrosion, and replacing a faulty shift solenoid control relay.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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