Transmission output speed sensor: symptoms and P0720

TSS output speed sensors for the 4L60E, 6T40 and 4F27E

In short

The output speed sensor (VSS or OSS) measures how fast the transmission's output shaft turns: the computer uses it for shifts, pressure and the converter, and on many cars for the speedometer too.
Typical symptoms are a speedometer stuck at 0 or erratic, no upshifts or starting in a high gear, limp mode and cruise control not working.
P0720 to P0723 mean a fault in its circuit: carmakers check the connector, wiring, debris on the sensor tip and its tone ring first.
It isn't the ABS sensor: ABS has its own wheel sensors, though on many newer cars the speedometer takes its speed from them.
On the 6R80 in the Lobo / F-150 the sensor is on the internal harness; in the US, Ford recalled 2011 to 2014 F-150s because they could suddenly downshift to 1st.

If the speedometer is stuck at 0, the transmission won't upshift or the scan tool shows P0720 or P0722, the problem is most likely the transmission output speed sensor, or its circuit. Here's what it is, where it is, its symptoms, what each code means, what carmakers check before replacing it and which one your car takes, according to GM, Ford, Nissan, Hyundai, Mazda, Subaru and Allison bulletins and manuals.

What is the output speed sensor and what does it do?

It measures how fast the transmission's output shaft turns. GM explains that the transmission computer uses that signal to set line pressure, shift timing, converter clutch slip and the gear ratio, which it calculates against input speed. On many cars the same signal is the "vehicle speed" that drives the speedometer, odometer and cruise control. It's called the VSS, OSS, vehicle speed sensor, secondary speed sensor (on Nissan CVTs) or pulse generator B (on Hyundai). It isn't the input or turbine sensor, which has its own codes (P0715 to P0718): see TSS transmission sensor.

On many newer cars, the speedometer takes vehicle speed from the ABS wheel sensors, and the computer compares the two signals. So, as GM warns, a working speedometer doesn't rule out the output sensor, and a failing one isn't always its fault.

Where is the output speed sensor?

On most automatics it's outside, bolted to the tailhousing or the case, and it's replaced without opening the transmission: that's the case, for example, on Chevrolet's 4L60E and Ford's 4R70W and 5R55E. On others it's inside: on the 6R80 in the Lobo / F-150 it's part of the internal harness, on top of the valve body; on GM's 6T70 the valve body cover comes off, and on Hyundai and Kia's 6-speed automatics the pan and valve body; and on the ZF 4HP16 in the Optra it sits under the valve body. On some GM 4x4 trucks, the sensor is in the transfer case.

Symptoms of a bad output speed sensor

The speedometer stays at 0, moves on its own or stops working, and the odometer may show dashes.
The transmission won't upshift, starts in a high gear or goes into limp mode. It depends on the unit: the 6R80 starts in 5th, the 4L60E holds 2nd and the 6T70 allows only reverse and 5th.
Harsh or mistimed shifts.
Cruise control stops working.
Check engine or transmission light, and on some trucks the ABS light too, because they share the signal.
A sudden downshift to 1st: if it happens, pull over carefully and have it checked before driving on.

Watch for look-alikes: if the car won't crank in P or the reverse lights don't work, the range sensor is more likely. On recent Nissans, when the vehicle speed signal fails, Nissan checks the ABS codes first. Different tire sizes or a different axle ratio also throw off the speedometer and the shifts, as GM warns. And if the problem is that it won't shift, see transmission not shifting.

Codes P0720, P0721, P0722 and P0723

Code	What it means and what to check
P0720	Output speed sensor circuit fault. Check the sensor reading on the scan tool while driving, the connector (moisture, corrosion, pins), the wiring, debris on the sensor tip and its tone ring.
P0721	The signal is there but doesn't make sense (range/performance): noise, an intermittent contact, a damaged or loose tone ring or a wrong air gap. Compare it with input and wheel speeds, and look for software updates.
P0722	No signal from the output sensor. Check the supply (on Hall-effect sensors), open or shorted wires, the connector and the sensor; Mazda fixed it on some models with a module reprogram.
P0723	Intermittent signal. Check loose connections, debris on the sensor and its bolt torque: GM says it's critical.
P0500 to P0503	Vehicle speed sensor. Depending on the brand, it can be the same output sensor or the ABS signal.

Some brands add their own codes: Ford also logs P0731 and P1500 when the 6R80's output sensor fails; Chrysler compares output speed with wheel speed (P215C and P1720); Nissan can set P1574, the cruise control's; and GM sets C0055 in the ABS module when the shared signal fails. Note: P0725 isn't the output sensor, but the engine speed signal.

Before replacing the sensor: what carmakers check

Hyundai puts it plainly in a US bulletin: don't replace the transmission for these codes. The order GM, Nissan and Hyundai follow is:

Watch the output speed on the scan tool while driving: GM says to drive at 10 to 20 mph and check that the reading rises and falls with speed without dropping out. If everything passes, GM says to stop testing to avoid replacing parts unnecessarily.
Check the connector: Nissan found moisture and corrosion on its CVTs' sensor pins, and Hyundai damaged or partly inserted pins.
Check the wiring with a meter, not the scan tool or the speedometer, as GM warns.
Check the sensor tip and its tone ring: per GM, metal debris on the tip, damaged gear teeth or a tone ring with play disturb the signal, and the sensor bolt torque is critical.
Test by type: magnetic sensors make their own signal, and Hall-effect sensors are powered by the computer (GM calls for 8.3 to 9.3 V on the 6T70). The number of wires doesn't always tell the type: compare with your transmission's manual.
Rule out software and grounds: Mazda and Allison fixed cases like this.
Only then, replace the sensor or the part that carries it: the internal harness on Ford's 6R80, or the valve body on some Nissans.

After the repair, GM calls for resetting the transmission's adaptive learning, and Ford notes that the computer relearns the shifts as you drive.

The 6R80 in the Lobo and F-150: the sensor on the internal harness

On the 6R80, the output sensor is on the transmission's internal harness. A US Ford bulletin describes trucks that start in 5th, with the speedometer at 0, dashes on the odometer and codes P0720 and P0722; the fix is a new internal harness, without replacing the solenoids. And between 2016 and 2026 Ford recalled, five times in the US, 2011 to 2014 F-150s and some 2012 Expedition, Navigator and Mustang models, because an intermittent sensor failure could suddenly downshift the transmission to 1st; the fix was a software update and, in some cases, the internal harness. In Mexico, the Lobo uses the same 6R80, but we found no PROFECO alert for this problem (we checked on October 27, 2026). More in 6R80 problems.

Which TSS output speed sensor does your car take?

These are the TSS output sensors and the cars they fit, per our guides to each transmission. On several units the sensor changed by year, connector or bore size, so compare it with yours before ordering. On the Jetta A4's 01M, the input and output sensors use the same connector type; see 01M problems:

Vehicle	TSS sensor
Chevrolet Silverado, Cheyenne, Tahoe, Suburban, Colorado and Trailblazer with the 4L60E	from 1996, small-bore sensor; through 1995, large-bore sensor
Ford Lobo / F-150 1997 to 2000 and Grand Marquis (4R70W)	4R70W output sensor; for 2001 to 2003, compare with the old one
Ford Lobo / F-150 2004 to 2008 and Expedition 2005 and 2006 (4R70E and 4R75E)	2004-and-later output sensor: it must match its tone ring's generation
Ford Explorer 4.0 5-speed through 2001, Explorer Sport and Sport Trac 2001 to 2005 (5R55E)	case-mounted output sensor
Ford Focus 2000 to 2011 and EcoSport 2.0 automatic through 2012 (4F27E)	4F27E output sensor
Ford Edge V6 2007 to 2018 and Explorer V6 2011 to 2019 (6F50 and 6F55)	3-pin output sensor
Ford Escape 2001 to 2008 (CD4E)	gearless output sensor
Ford Windstar, Taurus and Mercury Sable	AX4S from 1999: 96958D; AX4N 1995 to 1999: 96958A
Chevrolet Cruze 2010 to 2016, Trax, Equinox 2018 to 2021, Malibu and Buick Encore (6T40 and 6T45)	output sensor with pigtail
Chevrolet Malibu 4-speed and Captiva Sport 2.4 2008 to 2010 (4T40-E and 4T45-E)	4T45-E speed sensor
Chevrolet Optra 2007 to 2009 (ZF 4HP16)	output sensor; it sits under the valve body
Chrysler Voyager, Town & Country, PT Cruiser, Cirrus and Stratus, and Dodge Journey 2.4 (41TE)	24 mm output sensor
Jeep Liberty, Wrangler and Nitro, and Dodge Dakota and Ram 3.7 (42RLE)	42RLE output sensor
Dodge Grand Caravan, Chrysler Town & Country 2008 on and Journey V6 (62TE)	transfer shaft speed sensor, one of its three speed sensors
Volkswagen Jetta A4 2.0 and New Beetle 2.0 through 2007 (01M)	3-pin sensor or 2-pin sensor, by connector; the output one is G68
Volkswagen Bora 2.5, Jetta 2.5 2011 to 2018, Beetle 2.5 and Passat (09G)	blue-connector sensor; confirm by part number whether it's the input or the output one

On the Lobo / F-150 and Expedition with the 6R80, Hyundai and Kia's 6-speed automatics, GM's 6L80 and Nissan's newer CVTs, the sensor is inside or part of another component, and isn't in this list. The 4L60E's problems, including holding 2nd when the signal is lost, are in 4L60E problems.

See TSS sensors

TSS sensors

TSS has input and output speed sensors, range sensors, switches and solenoids for most automatic transmissions in Mexico. Confirm the model, year and transmission before ordering.

TSS is an aftermarket brand with OEM-comparable quality and quality control on every product. It's sold through our authorized distributors: in Mexico, the full TSS catalog is at Transmisiones Veinte 07, and in the United States at Sun Transmissions.

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