2002 Suzuki Grand Vitara

MY SERVICE ENGINE LIGHT CAME ON AND I THOUGHT IT WAS TIME FOR AN OIL CHANGE. WHILE I WAS GETTING THE OIL CHANGED THE MAN TOLD ME IT WAS NOT THE OIL CAUSING THE LIGHT TO COME ON BUT A CODE CALLED A{ E G P}
FLOW MALFUNCTION CAN YOU TELL ME WHAT THAT IS.