:sensor). Code 12 is the MAF circuit - did you install a brand new MAF or a "new" used one? Check the connections at the MAF and the temp sensor to be sure everything is in place. Also check for vacuum leaks at the MAF and elsewhere along the plenum. Look under the throttle bodies and make sure the vacuum ports have the hoses connected. :And what aftermarket gauge was reading 0? Is it a boost guage? A tach? :Dave