OBD-II trouble code
P0722: Output Speed Sensor Circuit No Signal
The transmission is getting no signal at all from the output speed sensor — the reading has gone to zero or flatlined while the car is clearly moving. This is the most clear-cut of the output-speed codes: not a wrong value, but nothing. Expect a dead or frozen speedometer, a transmission that often falls straight into limp mode, and a fault that's usually a broken circuit or failed sensor rather than a subtle calibration issue.
Quick facts
- System
- Powertrain
- Category
- Transmission / Speed Sensor
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $150 – $600
- DIY difficulty
- Intermediate DIY
What does P0722 mean?
P0722 sets when the PCM/TCM sees no output speed signal while other data — engine RPM, input speed, the fact that you're driving — says the output shaft must be turning. The output speed sensor reports how fast power is leaving the transmission toward the wheels, and the controller relies on it to calculate gear ratios, time shifts, and on most vehicles to drive the speedometer and feed ABS/traction systems. When that signal reads zero or is entirely absent, the TCM can't compute what gear it's in, so it commonly drops into a limp/failsafe mode — holding a single gear (often third) — to keep the car driveable while protecting the transmission. This is the 'no signal' end of the output-speed family, distinct from P0721 (signal present but implausible) and P0720 (general circuit malfunction).
A complete loss of signal points to a broken or open circuit far more than to a marginal one. The usual culprits are a failed output speed sensor, an open or shorted wire, a disconnected or badly corroded connector, or a damaged reluctor/tone ring that the sensor can no longer read. Connector problems — a harness that's come loose or pins that have backed out — are common and worth checking before condemning the sensor. Because the signal is fully gone rather than glitching, this code is often easier to pin down than its intermittent cousin P0718: the fault is present continuously, so live data and circuit testing show it plainly.
For the driver the signs are hard to miss: a speedometer that reads zero or doesn't move, an immediate drop into limp mode with a fixed gear and firm shifts, possible ABS/traction warning lights, and no torque-converter lockup. The car will usually still move but with degraded shifting. Diagnosis is straightforward by speed-sensor standards — confirm the signal is truly absent in live data, then test the sensor, its connector, and the wiring for an open circuit, and inspect the tone ring.
Common causes
- Failed output speed sensor producing no signal
- Open or shorted wiring in the sensor circuit
- Disconnected or badly corroded sensor connector
- Damaged reluctor / tone ring the sensor can no longer read
- Backed-out or broken connector pins
- Loss of sensor power or ground from a wiring fault
- Severe internal damage that has displaced the sensor or tone ring
Symptoms
- Check engine light with P0722 stored
- Speedometer reading zero or not moving while driving
- Immediate drop into limp / failsafe mode with a fixed gear
- Firm or harsh shifts and no torque-converter lockup
- ABS or traction-control warning lights on some vehicles
- Inability to calculate gear ratio, confusing shift behavior
Diagnostic steps
- 1.Confirm in live data that output speed truly reads zero while the vehicle is moving — this verifies a genuine no-signal condition.
- 2.Inspect the sensor connector for disconnection, corrosion, and backed-out pins, which are common and quick to find.
- 3.Check the wiring for an open or short, and verify the sensor has proper power and ground where applicable.
- 4.Resistance-check the sensor against specification; a reading far out of range or infinite indicates a failed sensor.
- 5.Inspect the reluctor / tone ring for damage that would leave the sensor with nothing to read.
- 6.Repair the open circuit or replace the sensor, then confirm output speed reads correctly and limp mode clears.
Repair cost
$150 – $600
Replacing the output speed sensor typically runs $150-$400 with labor depending on access. Repairing an open wire or a corroded connector can be less. Costs climb only if the no-signal condition traces to a damaged tone ring or internal transmission damage that requires opening the unit. Because the fault is continuous rather than intermittent, diagnostic labor is usually modest.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with transmission speed sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.