Advice for an engine code needed

Wifes 99 E-300 turbo diesel recently had service engine light come on. Three days later I discovered a break in the exhaust pipe two feet past the turbo. Had the exhaust welded at a custom exhaust shop and then went to Benz to read the code. The error code read, Mass Air Flow Sensor. They cleared it but it returned. Would the exhaust leak be the cause of the code, or am I looking at replacing the MAF or can it be cleaned with any success? Car has 166,000 km. on it and I service the air filter regularily. Thanks to all who can help. GPS>