Hi all, 2003 XC70 wagon, 2.5L turbo, AWD. Just had reduced engine performance (REP) mode activate while driving at high speed (75mph to 80mph). No codes were displayed, and no check engine light showed. I was able to get the car out of REP mode, the big question is, why did this happen in this speed range? I have a theory that fuel flow might be less than the car needs at these speeds, and so it kicks into REP to slow the car down. This cause-effect has happened twice, and my goal, of course, is to eliminate spurious REP activation. Several modules have been replaced, and REP frequency has been greatly reduced from what it used to be. I would love to hear your experiences/suggestions/ideas/theories. Thank you.

 

First step is to scan the car and check every module for codes. Even if there is no CEL, there is guaranteed a code stored in a model related to your REP.

 

+1 - the codes should tell you if there were misfires/fuel trim issues etc.