Transmission

P0801 — Reverse Inhibit Control Circuit Malfunction

Severity: medium Drive with care, to a shop

What P0801 means

The transmission control module monitors the electrical circuit of the device that prevents reverse from being selected while moving forward. If voltage or resistance in that circuit is out of range, the module stores P0801 and may block reverse or allow it when it should not.

Symptoms

  • Reverse will not engage
  • Check Engine or transmission warning light on
  • Start-in-gear protection works incorrectly
  • Harsh or hesitant shifting when selecting R
  • Shifter feels locked or fails to latch

Possible causes

  1. Failed reverse inhibit solenoid
  2. Faulty range (shifter position) sensor
  3. Transmission control module fault
  4. Open, shorted or damaged wiring
  5. Corroded or loose connector
  6. Misadjusted shift linkage

How to diagnose

  1. Scan for codes, save freeze frame data and look for other transmission codes
  2. Inspect the solenoid and range sensor connectors and wiring for damage, moisture and corrosion
  3. Check supply voltage and ground at the solenoid with a multimeter
  4. Measure solenoid resistance and compare with the vehicle's specification
  5. Check the range sensor signal through every shifter position
  6. Inspect shift linkage condition and adjustment
  7. Test wires to the control module for opens and shorts
  8. If circuits are good, test the module and check for a software update

Common fixes

  • Replace the reverse inhibit solenoid
  • Replace or adjust the range sensor
  • Repair wiring and clean or replace the connector
  • Adjust the shift linkage
  • Reflash or replace the transmission control module

Questions and answers

What does P0801 mean?

It indicates an electrical fault in the reverse inhibit circuit. The control module sees values outside the normal range and reports the problem.

Can I drive with P0801?

Usually yes, but with care, since reverse may not engage. It is best to fix the cause soon.

What most often causes P0801?

Typically the inhibit solenoid, the range sensor, or wiring and connector problems. Start with a wiring inspection and circuit tests.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.