Transmission

P0723 — Output Speed Sensor Circuit Intermittent

Severity: medium Drive with care, to a shop

What P0723 means

The output speed sensor tells the engine or transmission control module how fast the transmission output shaft is turning. That signal is used to calculate vehicle speed and decide when to shift. P0723 sets when the signal drops out, returns or becomes erratic without a clear reason.

Symptoms

  • Speedometer needle drops to zero or jumps at times
  • Check Engine light, sometimes a transmission warning light
  • Harsh, late or erratic shifts
  • Transmission stuck in one gear (limp mode) from time to time
  • Cruise control not working or cutting out
  • Code that comes and goes

Possible causes

  1. Worn or failing output speed sensor
  2. Loose, corroded or dirty transmission connector
  3. Wire rubbing against the driveshaft shield or body
  4. Open circuit or poor connection in the harness between sensor and control module
  5. Faulty vehicle speed sensor (VSS) or ABS wheel sensor if the signal is shared
  6. Metal debris on the sensor or dirty transmission fluid
  7. Rarely, a failed ECM, PCM or TCM

How to diagnose

  1. Scan all codes and read freeze frame data to see when the fault occurred
  2. On a test drive, compare output shaft speed, ABS speed and speedometer in live data
  3. Inspect the sensor connector for a loose lock, corrosion, moisture and bent pins
  4. Check the harness along its whole length, especially near the driveshaft, shield and mounting points
  5. Wiggle the harness and connector with the engine running and watch for signal dropouts
  6. Remove the sensor and look for wear, debris and damage; test resistance or signal per factory specs
  7. Check transmission fluid level and condition
  8. Suspect the control module only after confirming its power and ground

Common fixes

  • Replace the output speed sensor
  • Clean the connector or replace it and repair the terminals
  • Repair or replace damaged wiring and secure the harness
  • Change the fluid and clean debris from the sensor if that was the cause
  • Replace a faulty VSS or ABS sensor
  • Reflash or replace the control module if everything else checks out

Questions and answers

What does P0723 mean?

The control module is getting an unstable, dropping signal from the transmission output speed sensor. This can upset the speedometer and the way the transmission shifts.

Can I drive with P0723?

For a short distance and with care, such as to a shop. The transmission may shift harshly or go into limp mode, so don't put the repair off.

How do I fix P0723?

Start by inspecting the connector and wiring near the transmission and driveshaft. If those are fine, the output speed sensor is usually what needs replacing.

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.