Description of DTC code P0721

The Output Shaft Speed Sensor (OSS) provides the Powertrain Control Module (PCM) with a signal indicating the speed at which the transmission output shaft is rotating. These readings are used by the PCM to control the shift solenoids.

The solenoids carry fluid to various hydraulic circuits, in addition to changing the transmission gear ratio when necessary. The OSS Sensor can also control the speedometer reading, although this varies by manufacturer.

When DTC P0721 OBD2 is set, it is because the PCM has found a malfunction in the OSS Sensor circuit. This sensor is not working properly or is out of range.

Symptoms of fault code P0721

  • Check Engine light ON.
  • Decreased fuel efficiency.
  • The transmission shifts abruptly or may not allow shifting at all.
  • The speedometer shows an erroneous reading.

Causes of OBD2 P0721

Reasons to set the P0721 OBDII fault code:

  • The cable system or cable connections may be having problems.
  • Possibly the Output Shaft Speed Sensor (OSS) is faulty.
  • The transmission filter may have clogging of contaminating elements.
  • The Coolant Temperature Sensor (ECT) may be defective.
  • The shift solenoid may be defective.

Possible solutions of the DTC code P0721

To clear the P0721 OBD2 error code faults, try this:

  • Check the condition of the transmission fluid. and make sure the level is adequate for proper operation. If necessary, change it.
  • Remove the OSS Sensor and inspect the sensor teeth and resistance. Replace it if there are some problems.
  • Check wiring harness for loose connections or damaged wires. If inconsistencies are found, repair or replace.

Codes related to P0721

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