95 G20 - can't find ECU -

The check engine light came on last week in my G20 (w/97k miles), and there has been little to no difference in performance.

My mechanic said to replace the 02 sensor and reset the ECU. Looked for it in two places described in other post -

1) lower center panel, right side, next to gas pedal - found a silver box, a little bigger than a pack of cigarettes, with a white plastic shield protecting a harness. Put a socket on the 10mm bolt holding the shield in place and it won't budge, and I don't want to put to my pressure on it for fear of screwing up the harness.

2) panel by left passenger foot/clutch pedal - found a blue and white box, about 1 x 2 inches, has wires coming out of it, looks like a relay.

Neither of these appear to have an LCD and a screw...am I not recognizing the ECU, or is it somehwere else?

and...

will disconnecting the battery for 12+ hours turn off the check engine light, assuming it was the 02 sensor that caused the light to go on?

thanks in advance...

I looked a little harder and found the ECU right where it's supposed to be, center console, left side of passenger compartment.

Received three codes: 3-2, 3-5, 9-1. Looked at imagestation.com, and it seems that 3-2 and 3-5 are for California cars only? Is that correct? My G was bought and lived in NY/CT its entire life, no Cal emissions at all.

The check engine light went out too.

on my primera 94/95 right hand side drive i found on passenger side left kick panel a large blue box in the centre console on the floor at the back another large silver box with red led screwed down to the floor and infront of that under the ashtray was a smaller black box i am confused to whats what can any one help me thanks