P0720: Output Speed Sensor — Causes and Fix
Key Takeaway
P0720 is the output speed sensor. It monitors how fast the transmission output shaft spins.
What P0720 Means
The output speed sensor measures the transmission output shaft speed. The TCM uses this to determine vehicle speed and compare it against input speed for shift control.
Symptoms
| Symptom | Why |
|---|---|
| Speedometer reads zero or erratic | Output sensor feeds speedometer |
| Harsh shifting | TCM can't verify shift completion |
| No shifting (one gear only) | TCM enters limp mode |
| ABS/traction lights on | Systems use vehicle speed data |
| Cruise control inoperative | No reliable speed input |
Common Causes
| Cause | Fix Cost |
|---|---|
| Failed sensor | $80 – $200 |
| Wiring/connector issue | $50 – $200 |
| Metal debris on sensor | $0 (clean) |
| Old transmission fluid | $100 – $200 |
ProHow Steer Helps
Steer identifies P0720 and monitors vehicle speed data to confirm sensor failure.
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