Conditions for Setting the DTC
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The 4th clutch is commanded OFF and the hybrid powertrain control module detects the clutch 4 slip speed is less than 80 RPM for 3 seconds.