Diagnostic Aids

For Symptom Byte 21, the module only run diagnostic when the vehicle is driven greater than 40 km/h (25 MPH). Therefore, even with clean sensor with no obstruction (i.e. snow or ice melted off) drive the vehicle greater than 40 km/h (25 MPH).

The following is a list of reasons this failure type byte 21 might have set:

• One or more of the sensors may be blocked by snow, mud, ice or other debris. This might happen after going through a car wash in cold weather.
• Silicone insulator surrounding sensor maybe missing, cut or twisted.
• Improperly installed sensor, sensor maybe be crooked due to a tight wire harness.
• One or more of the sensors may be scratched or the paint maybe chipped.
• Excessive paint thickness on a sensor may cause an excessive sensor ring time. When replacing or refinishing a sensor, do not apply an excessive amount of paint or clear coat.