What P0720 means
The transmission isn't getting a usable signal from its output shaft speed sensor. Without it the car can't tell how fast it's going, so shifts get harsh or the transmission locks into one gear. The speedometer may stop working.
How the engine computer detects it
The output shaft speed sensor (Hall or inductive) reports the speed of the transmission output; it gives the gear ratio together with input speed and on many vehicles also the road speed for speedometer and cruise control. P0720 is the general circuit code. Ford also uses it for 'no signal': while engine and turbine speed show the vehicle moving, the sensor reports under 100–200 rpm for 5–30 s; ZF's 6HP26 in Ford vehicles flags an open or short after 0.6 s. Subaru-based systems (Saab 9-2X) flag an impossible 255 km/h (158 mph) or 0 km/h (0 mph) while driving and light the MIL after two trips, substituting the other sensor. GM does not use P0720 but P0722. Speedometer and cruise control may fail, often with a vehicle speed code as well.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Speedometer drops out or jumps
- Warning lamp, limp mode or fixed gear
- Harsh shifts, cruise control not working
Common causes
- Speed sensor faulty (Hall IC or coil open or shorted) Most likely
- Connector or harness corroded, chafed or loose pins (with internal sensors also the pass-through connector) Most likely
- Metal debris on the sensor magnet or damaged reluctor wheel Possible
- Transmission module or its sensor supply faulty Less likely
How to diagnose P0720
- Locate the output shaft speed sensor on the transmission case and check its connector and wiring for damage or corrosion.
- Remove the sensor and clean any metal debris from its tip.
- Measure the sensor with a multimeter or scope against the manual's values.
- Replace the sensor if it's out of spec. On many transmissions it's an inexpensive part bolted to the outside of the case.
Vehicles that report P0720 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ford F-150 | 2010–2017 | 125 | 122k | |
| Infiniti Q50 | 2014–2016 | 18 | — | |
| Ford Mustang | 2012–2014 | 6 | 67k | |
| Ford Expedition | 2013–2017 | 5 | — | |
| Ford Edge | 2007–2008 | 4 | 118k |
Counts of owner complaints to the NHTSA that mention P0720 (178 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 7
- Transmission
- 20
- Specific fault
Questions drivers ask
Can I drive with code P0720?
Drive gently to a shop. In limp mode the car can be stuck in a single gear, which makes highway driving unsafe.
Will my car pass an emissions inspection with P0720?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Can I fix P0720 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0720. They can point to a shared cause, so it's worth checking them together.
- P0722Output Shaft Speed Sensor Circuit No Signal47 complaints
- P0500Vehicle Speed Sensor A Circuit16 complaints
- P0721Output Shaft Speed Sensor Circuit Range/Performance9 complaints
- P0706Transmission Range Sensor A Circuit Range/Performance6 complaints
- P0705Transmission Range Sensor A Circuit (PRNDL Input)5 complaints
- P0707Transmission Range Sensor A Circuit Low4 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.