P0720 Code: Output Speed Sensor — Causes & Fix
P0720 means a fault in the transmission output speed sensor circuit — the sensor that reports gearbox output (road) speed for shift control.
- Applies to
- All OBD-II vehicles (any make or model)
- Est. repair cost
- $40 – $500
- Time to fix
- 30 minutes – 2 hours
What it means
Causes include a failed output speed sensor, a damaged reluctor, wiring faults, or low fluid. P0720 is a generic OBD-II powertrain code defined in the SAE J2012 standard, so it applies to virtually any 1996-or-newer petrol car or light truck regardless of make. Fix the underlying fault, then clear the code with an OBD-II scan tool — it will return if the problem isn't resolved.
Symptoms
- Check engine light on
- Erratic speedometer
- Harsh or erratic shifting; possible limp mode
How to fix it
- 1
Inspect the sensor and wiring
1. Locate the output speed sensor on the transmission. 2. Check the connector and wiring; confirm fluid level.
- 2
Test and replace
1. Verify a clean speed signal on a scan tool. 2. Replace a faulty sensor, then clear the code.
Frequently asked questions
Can P0720 cause bad shifting?
Yes — the transmission relies on output speed to time shifts, so a faulty sensor causes harsh, erratic, or delayed shifts.
Last updated July 19, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.