P0723
Output Speed Sensor No Signal
Powertrain Transmission Control Output Speed Sensor 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your transmission's speed sensor isn't sending a signal to the engine computer, like a speedometer that stopped working. Without this feedback, the transmission can't shift properly or control itself effectively.

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Symptoms You May Notice
3 known symptoms for this code
Transmission won't shift or shifts erratically
Check engine light illuminated
Reduced fuel economy or limp mode activation
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors voltage pulses from the output speed sensor (OSS) to determine transmission shaft speed and select appropriate gears. The sensor typically generates an AC or digital signal proportional to transmission output rpm. When no signal is detected for a set duration, the ECM logs fault P0723.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Output Speed Signal Frequency Continuous AC/digital pulses proportional to vehicle speed Zero signal or below detectable threshold for >2 seconds
Signal Voltage 0.5-5V AC or 0-5V digital No voltage variation detected
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wiring harness and connectors
Inspect OSS connector for corrosion, loose pins, or damage; clean or reseat connections.
2
Output Speed Sensor (OSS)
Unbolt the faulty sensor from transmission housing and install a new one with proper gap.
3
Transmission wiring harness
Replace damaged wires between sensor and ECM if corrosion or breaks are found.