Would not be unusual for the IMRC to go out. You can check its operation by watching the IMRC linkage/cable open the secondaries at around 3800 RPM when revving the engine by hand. The secondary butterfly valves may be gunked up with carbon, causing them to stick. Post the code to get more detailed info/help, or look up your code
here (Sounds like a P1512/13??) You'll be happy to get this fixed.
