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DTC codes / P07xx · Transmission / P0723

P0723Output Speed Sensor Circuit Intermittent

P0723 means the transmission control module (TCM) has detected an intermittent or erratic signal from the output speed sensor, which monitors the rotational speed of the transmission output shaft. The computer sets this code when the signal momentarily drops out or becomes inconsistent while the vehicle is moving, rather than failing completely.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • The check engine light or transmission warning light illuminates on the dashboard.
  • The transmission may shift harshly or at the wrong time, especially during acceleration or deceleration.
  • The speedometer may fluctuate or stop working intermittently if the output speed sensor also feeds the speedometer.
  • The transmission may enter limp mode, sticking in a single gear to protect itself.
  • Often no symptoms besides the warning light, especially if the intermittent fault is brief and infrequent.

Common causes, most likely first

  1. A faulty output speed sensor that is failing intermittently due to heat or internal damage.
  2. Damaged or corroded wiring and connectors between the sensor and the transmission control module.
  3. Metal debris or contamination on the sensor tip, disrupting the magnetic pickup.
  4. A damaged or improperly installed sensor reluctor ring or tone wheel on the output shaft.
  5. Loose or worn sensor mounting that allows the sensor to move and lose signal.
  6. Electrical interference from aftermarket accessories or poor grounds affecting the signal circuit.
  7. A failing transmission control module or internal transmission problem, though less common.

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, and record freeze-frame data to see when the fault occurred.
  2. Visually inspect the output speed sensor, its wiring, and connectors for damage, corrosion, or loose pins.
  3. Check the sensor resistance and signal output with a multimeter or oscilloscope while wiggling the harness to catch intermittent faults.
  4. Remove the sensor and inspect the tip for metal shavings or debris; clean or replace if contaminated.
  5. Verify the reluctor ring or tone wheel is intact and properly secured, and check sensor air gap if adjustable.
  6. Perform voltage drop tests on the sensor ground and signal circuits to rule out high resistance.
  7. If all external checks pass, substitute a known-good sensor or use a lab scope to confirm signal integrity before replacing the TCM.

Intermittent faults hide in plain sight

  • A common misdiagnosis is replacing the output speed sensor when the real problem is a chafed wire in the harness that only shorts when the engine moves under load.
  • The output speed sensor signal is often shared with the speedometer and cruise control, so a flickering speedometer can be the first clue before any transmission symptoms appear.
  • Metal debris on the sensor tip from a failing transmission can cause an intermittent signal, so always clean the sensor and check the fluid for metallic particles.
  • Intermittent codes often do not set until the fault occurs a certain number of times, so a single scan may show no code even though the problem exists.
  • Aftermarket electrical accessories or a poor ground can introduce noise into the sensor circuit, mimicking a failing sensor.

Can I keep driving with P0723?

You can usually drive short distances to a repair shop, but avoid heavy acceleration or towing because intermittent speed signals can cause harsh shifts or limp mode. If the transmission behaves erratically or the speedometer fails, stop driving and have it diagnosed promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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