P0720 Code Meaning and Next Steps

First checks take 10 to 20 minutes for the first checks. No special tools are usually needed for the first checks.

Can you keep driving?

Stop driving if any of these apply

!The transmission slips, bangs into gear, or will not shift correctly.
!The vehicle loses drive, enters limp mode, or the warning light is paired with obvious transmission trouble.

If the light is steady and the vehicle still drives normally: Maybe, but only for a short distance if the transmission still shifts normally.

What to check first

Step-by-step checks

1
Free - no tools
Check whether the speedometer or vehicle-speed data looks wrong at the same time
2
Free - no tools
Inspect the output speed sensor connector and harness for damage, looseness, or contamination
3
Basic tool needed
Notice whether the code appeared after recent drivetrain work or a bump to the harness
4
Basic tool needed
If scan data is available, compare the output speed signal with actual vehicle movement
5
Basic tool needed
If other speed-sensor codes are present, diagnose the sensor network together rather than separately

If the code returns

-If the signal drops out under vibration, wiring or the sensor itself becomes more likely.
-If the code returns after reseating the connector, check the circuit under load.
-If the output speed data is good but shifting is still wrong, the issue may be deeper in the transmission control path.

Background

What this code means

P0720 is a generic OBD-II transmission code for the output speed sensor.

The transmission controller uses this signal to know how fast the output shaft is turning, so a bad reading can affect shift logic.

The speedometer may act oddly, shifts may feel wrong, or the transmission may not know vehicle speed correctly.

Diagnosis

Common causes

Most common

Failed output speed sensor

The sensor may no longer produce a stable speed reading.

Common

Connector or harness issue

A loose or damaged connection can interrupt the signal.

Common

Debris or contamination

Metal particles can distort the speed reading.

Possible

Controller-side fault

The TCM may be reacting to a broader transmission problem.

Avoid these mistakes

What not to do

xDo not keep driving if the transmission is slipping, flaring, or refusing to shift correctly.
xDo not assume the scan code tells you the exact failed part without checking the fluid, connectors, and symptoms first.

Parts

Parts that may need replacing

PartTypical costNotes

Output speed sensor$50-$180Most relevant when the signal itself tests poorly.

Connector pigtail repair$20-$120Worth checking if the plug or pins are damaged.

Transmission fluid service$80-$250Useful if contamination is part of the diagnosis.

Related OBD codes

P0700

P0700 usually means the transmission control system has a fault stored in the transmission module.

P0715

P0715 usually means the input or turbine speed sensor circuit is not behaving correctly.

P0722

P0722 usually means the output speed sensor has no signal.

Source notes

Generic OBD-II (SAE J1979 / ISO 15031-5). P0720 was expanded around common output-speed sensor faults, including sensor failure, wiring issues, and contamination.

This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.

This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.

Last reviewed: 2026-04-10

Reference: Open reference

P0720 - P0720 Usually Means the Output Speed Sensor Circuit Is Not Behaving Correctly