Diagnostic Aids
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
For symptom byte 21, the parking assist control module only runs the diagnostic when the vehicle is driven greater than 40 km/h (25 MPH). When diagnosing symptom byte 21, the vehicle must be driven greater than 40 km/h (25 MPH) after a repair to verify the concern has been corrected.
The following is a list of reasons this symptom byte 21 might have set:
- One or more of the sensors may be blocked by snow, mud, ice, or debris. This condition may occur after going through a car wash in cold weather.
- 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.
- The silicone insulator (ring) surrounding sensor maybe missing, cut, or twisted.
- The sensor may be improperly installed and not fully seated, or the sensor may be misaligned due to a tight wiring harness.