At the weekend I had the dash out & managed to pull the speedo cable off ...drove the car & got the expected 'engine check' light & 4.5K rev limit ...which again I expected because the speedo was dead

Decided to do an ECU check before refitting & got the following!

Code 23: MAF
Code 24: Idle Control Valve
Code 33: Speedo Sensor
Code 45: Pressure Sensor (Pressure Exchange Solenoid)

So, refitted speedo & performed a reset, drove a bit (with both green & black connectors still connected) & got a code 33 again? (but speedo now working)

Parked up, checked codes & again got all four again?

As a precauiton i checked the MAF by unplugging it ...car cut out virtually instantly ...so i pressume it's ok

Previously the car has ran fine ...apart from the odd hiccup under full load (which i thought was the boost soleniod sticking, but i hadn't managed to clean it properly yet)

So my question is: am i clearing the codes properly? ...& would a hiccupping boost soleniod cause the other error codes???

Any ideas?

This is on a '95 STi BTW