P0721

P0721 08

Output RPM Sensor Circuit, Faulty Signal







Fault symptom
- Messages shown in SID.

On-board diagnosis

Type of diagnosis:
- Continuous

Enable criteria:
- Engine running and not in limp home mode.

Exceptions:
- Reverse gear engaged.
- 2nd or 3rd gear engaged.

Fault criteria:
- Control module receives no voltage from the output speed sensor.
- Control module receives no value from output speed sensor but receives value from the input speed sensor.

System reaction to a fault:
- Control module uses speed value from the ABS system instead of the output speed sensor.

If the DTC remains during several test cycles:
- Limp home

Checking the wiring harness
- Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.

Diagnostic help

Diagnosis regards:
- Electrical fault in connecting leads or component.