DTC P1646:00, P1647:00 [MZI-3.7]: Notes

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DETECTION CONDITION & POSSIBLE CAUSE

DTC P1646:00 DTC P1647:00	A/F sensor (RH) control chip A/F sensor (LH) control chip
DETECTION CONDITION	P1646:00 indicates the A/F sensor (RH) control chip. P1647:00 indicates the A/F sensor (LH) control chip. The PCM monitors the application-specific integrated circuit that controls and monitors the HO2S. The test fails when the PCM detects an internal circuit or communication concern.
POSSIBLE CAUSE	PCM malfunction