Output Speed Sensor Circuit No Signal
The P0722 code indicates that the Powertrain Control Module (PCM) or Transmission Control Module (TCM) is not receiving a signal from the transmission Output Shaft Speed (OSS) sensor. The computer sets this code when it detects that the vehicle is moving based on other sensor inputs, but the output speed sensor registers zero RPM.
This code requires immediate attention because the transmission relies on this signal to shift correctly. Driving with this code can result in harsh shifting, limp mode, or potential internal transmission damage.
Common symptoms
- Illuminated Check Engine Light
- Erratic or harsh transmission shifting
- Transmission stuck in limp mode (failsafe gear)
- Inoperative or erratic speedometer
- Decreased fuel economy and poor acceleration
Likely causes
- Faulty Output Shaft Speed (OSS) sensor
- Damaged, corroded, or loose wiring harness and connectors
- Metal debris on the magnetic tip of the OSS sensor
- Dirty or contaminated transmission fluid
- Internal transmission mechanical failure
- Faulty PCM or TCM (rare)
What to check before replacing parts
Visually inspect the OSS sensor wiring and connector.
Look for: Look for frayed wires, melted insulation, or corroded pins that could interrupt the signal.
Check the transmission fluid level and condition.
Look for: Look for heavily burnt fluid or excessive metal shavings, which can interfere with the magnetic sensor's ability to read the reluctor wheel.
Monitor the OSS sensor data using a live data scan tool.
Look for: Drive the vehicle and observe the OSS PID; if it reads 0 RPM while moving, the sensor or circuit is completely dead.
Test the OSS sensor resistance with a multimeter.
Look for: Compare the resistance reading across the sensor terminals to the manufacturer's specifications; an open circuit (OL) indicates a failed sensor.
Check the sensor signal output using an oscilloscope.
Look for: Look for a clean, consistent square or sine wave pattern that increases in frequency with vehicle speed; a flatline confirms no signal is being generated.
This page explains the generic P0722 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
Gear guide: Best OBD2 ScannersRead this code yourself next time — from $20 Bluetooth dongles to bidirectional scan tools.Rather have a pro handle it? Find a vetted local mechanic.