July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

DTC P1602: Immobilizer Unit-Pcm Communication Error: Notes

WARNING: This page is about a different car, the 2004 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: DTC P1602 Detection Condition & Possible Causes Chart

Courtesy of MAZDA MOTORS CORP.