DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610: Description
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The DTC P0606 Control Module Internal Performance sets when the powertrain control module (PCM) has determined that the control module has an internal fault. The PCM performs continuous self checks of all internal circuits. There are two central processing units (CPU) within the control module. If the outputs from the two CPUs deviates from the standard level, a DTC P0606 sets.