Hello, new to the group. My son and I just purchased 2011 Lancer Ralliart, which runs really well until at WOT and under boost the service engine light comes on, and stays on. The car is stock, no tune.
We have had the code P0068 checked by our local mechanic, and now a Mits dealer. MAF and Over-boost... The dealer confirmed that the car was only at 21 psi and was not over-boosting; just suggested changing MAF which we have done. Again, light comes on and it seems that engine management system creates slight decreased performance when light is on; no horrible limp mode; but just not as peppy as normal?
Thanks in advance

 

Hello and welcome. Please post up the exact CEL code. That might help us help you

 

Thank You! P0068

 

It's been a while since I've seen stock boost so correct me if I'm wrong but on bone stock isn't 21PSI over boost? Usually 16 or 18 stock right?

Have you checked the boost pill?

The previous owner may have had it tuned with a boost pill and changed the tune back to stock to sell it but forgot to put the original pill back in.

 

21 is high for a stock RA. Check for mods and tune just in case. A test pipe or HFC can also lead to overboost conditions