Possible Causes

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

Possible causes are:

Connector or terminal malfunction
EGR boost sensor malfunction
Open circuit in Pink wire between EGR boost sensor 3-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 34
Open circuit in Red/Black wire between EGR boost sensor 3-pin harness connector terminal "C" and PCM 104-pin harness connector terminal No. 90
PCM malfunction
Short to ground circuit in Pink wire between EGR boost sensor 3-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 34