Low Output Speed Sensor RPM Above 15 Mph (OBD II)

Name of Code:
166 ($A6) - Low Output Speed Sensor Output Above 15 MPH.

When Monitored:
Continuously with the key on, engine running, and gear selector not in park or neutral.

Set condition:
This code is set if the vehicle speed (as determined from the vehicle speed sensor), is above 15 MPH, and the output shaft speed is below 60 RPM for 2.6 seconds.

Theory of Operation:
The Output Shaft Speed Sensor (OSS) is a variable reluctance (magnetic) sensor. As the parking pawl lugs pass the OSS, a magnetic field is induced in the sensor, this results in a voltage output from the sensor. The output from the sensor is a sine wave that changes in frequency and amplitude relative to output shaft speed. The higher the frequency and amplitude, the higher the output shaft speed.

Transmission effects:
There are no noticeable driveability effects. The output shaft speed is calculated from vehicle speed. The MIL will illuminate.

Possible Causes:
- Corroded. damaged. pushed out, miswired, or disconnected connector(s)
- Faulty Output Shaft Speed Sensor
- Worn or damaged parking pawl lugs
- Internal controller failure (PCM)