OBD codes / P0720
P0720
SeriousOutput Speed Sensor Circuit Malfunction
Treat P0720 with some urgency. Beyond a possibly dead speedometer, erratic shifting or limp mode is hard on the transmission. It's usually drivable gently to a shop — check the fluid level first — but don't take long trips or tow until it's diagnosed.
What this code means
The output speed sensor measures how fast the transmission's output shaft is turning — essentially road speed at the transmission. The computer uses it for shift timing, torque-converter lockup, and often the speedometer and cruise control. P0720 means that signal is missing or erratic. Common causes are a failed sensor, wiring/connector trouble, or low/dirty transmission fluid. Symptoms range from harsh or erratic shifting to a dead speedometer, depending on the vehicle.
Symptoms you might notice
- Erratic, harsh, or delayed shifting
- Speedometer reads zero or jumps around
- Cruise control won't engage
- Transmission limp mode in some cases
- Check-engine light
What it costs to fix
Typical range: $120–$600 · about ~0.5–4 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Output speed sensor | $30–$150 | ~0.5–4 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
| Transmission fluid service | $80–$250 | ~0.5–1.5 hrs |
The sensor is cheap; labor depends on access — many output speed sensors are external and easy, but some require dropping the pan or more. A damaged reluctor ring is a bigger job that varies.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0720 for my exact vehicle →
Frequently asked
Can I drive with P0720?
Carefully and not far. A wrong or missing speed signal can cause erratic shifting and may disable the speedometer and cruise control. Check the fluid and get it diagnosed before any long drive.
Why is my speedometer not working with P0720?
On many vehicles the output speed sensor also feeds the speedometer, so a fault can make it read zero or jump. Fixing the sensor usually restores the speedometer along with proper shifting.
What's the difference between P0715 and P0720?
P0715 is the input (turbine) speed sensor at the front of the transmission; P0720 is the output speed sensor at the back. The computer compares the two to manage shifts — and either one failing throws shifting off.
How much does it cost to fix P0720?
The sensor is inexpensive; cost hinges on access — external sensors are cheap to swap, internal ones cost more. A fluid service is modest. Diagnosis confirms the labor before you commit.
Seeing P0720 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0720 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.