DTC Advanced Diagnostics: P0721
DTC P0721:Output Shaft (Countershaft) Speed Sensor Out of Range

General Description

The powertrain control module (PCM) monitors the vehicle speed converted from the output shaft (countershaft) speed sensor to detect malfunctions. If the output shaft (countershaft) speed sensor output is a specified value for a specified duration, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Continuous
Sequence
None
Duration
6.0 seconds or more
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
 
Vehicle
ON mode

Malfunction Threshold
The output shaft (countershaft) speed sensor outputs 156 mph (250 km/h) or more for at least 6.0 seconds.

Possible Cause
NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
Output shaft (countershaft) speed sensor failure
PCM internal circuit failure

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool clear command or by disconnecting the 12 volt battery.