Advanced Diagnostics

DTC P0723: Output Shaft (Countershaft) Speed Sensor Intermittent Failure




General Description
The countershaft speed sensor is attached to the outside of the transmission housing. The countershaft speed sensor generates a pulsing signal according to the speed of the park gear on the countershaft. Using that signal, the powertrain control module (PCM) determines the speed of the countershaft. If pulse dropouts occur with the countershaft rotating, the PCM detects a malfunction that may be caused by an open, a temporary open, or a short to ground. Based on the fluctuation of the vehicle speed measured by the countershaft speed sensor, a malfunction is detected and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
The fluctuation of the vehicle speed measured by the countershaft speed sensor in 10 milliseconds is 4 mph (6km/h) or more, and it fluctuates at least six times within 500 milliseconds.

Driving Pattern
Start the engine, and drive the vehicle at a speed of 13 mph (20 km/h) or more so it shifts from 1st to 5th in D position.

- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected during the first drive cycle, a Temporary DTC is stored in the PCM memory. If the malfunction recurs during the next (second) drive cycle, the MIL comes on and the DTC and the freeze frame data are stored.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, the Temporary DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.