2005 Honda civic ex will not go past 4000rpm
 

Had my oil changed. New alternator. New o2 sensor. Passed smog. Now im driving & I look at the dash to see my good ole engine light on. So I kept driving and found out I can't exceed 4000rpm. . I took it to a mechanic. He said I need to change the oil. (Well thats what his little code reader said).. HELP PLEASE. :-)

sounds like it mite be in limp mode what exactly was the code or codes that were given ???