P0720 code: Output Speed Sensor Circuit Malfunction
P0720 means output Speed Sensor Circuit Malfunction. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0720 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.
P0720 symptoms
- 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 P0720
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 →
How to fix P0720
Easy — basic tools, most owners can do this
- Note what else is acting up
A dead or jumpy speedometer alongside harsh shifting strongly corroborates an output-speed-sensor fault, since many vehicles drive the speedometer from this signal. It also tells you the problem is at the sensor or wiring rather than deep in the transmission.
- Inspect the sensor's connector and wiring
Find the output speed sensor on the tailhousing or transaxle case and check the connector for transmission fluid intrusion, corrosion, and chafed wires. Fluid wicking up into the connector is a classic failure on these and costs nothing to fix but cleaning.
- Verify fluid level and condition
Low or dirty fluid can interfere with sensor readings and shift quality at the same time. It's a two-minute check that keeps you from replacing a sensor to fix a fluid problem.
- Test, then replace the sensor
Watch output speed on a scan tool while driving — a signal that's dead or dropping out while the car is clearly moving condemns the circuit. Most output speed sensors are external: one bolt, one O-ring, one connector, making this one of the easier transmission repairs.
- Check the tone ring if a new sensor doesn't fix it
If the fresh sensor reads erratically too, the reluctor (tone) ring the sensor reads may be damaged — that's an internal inspection and a much bigger job. Wiring between sensor and computer should also be verified before going inside.
DIY or shop? This is usually a friendly DIY code: most output speed sensors sit externally on the case and swap out in minutes with hand tools, and the diagnosis needs only a scanner with live data. It becomes shop work in two situations — vehicles where the sensor is internal or the signal actually originates from the ABS system, and the rare case of a damaged reluctor ring, which means opening the transmission. Confirm your vehicle's sensor location before buying parts.
Tools for the DIY steps: OBD2 scanner with live data · Socket set · New sensor O-ring · Electrical contact cleaner · Shop towels for fluid drips
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0720.
Start a case with P0720 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0720?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0720: common questions
Can I drive with P0720?
A code alone can't settle that. 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 promptly, and if it slips, bangs into gear, or loses drive, stop driving and have it towed.
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.
Symptoms that trigger P0720
Drivers who get this code often notice one of these. Each has its own causes and cost guide:
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0720 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0720 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.