Code P0170 on 1999 Mercedes-Benz CLK320

My check engine light is on and I had the code checked, which the code is P170 - Fuel Trim Malfunction Bank 1. How much does it cost to repair this and what happens if I keep driving?

2 answers
here are some fuel trim code articles that I wrote for RepairPal to help customers and shops understand what is going on with this often confused code condition
I do Emissions work in CA and have dealt with these issues for years.
http://repairpal.com/OBD-II-Code-P0171-and-P0174
http://repairpal.com/OBD-II-Code-P0172-and-P0175

It would be best to find out more about the code P0170 i.e. are there any other codes, because this code just indicates there is a Fuel Trim Malfunction, usually there are other codes to indicate the fuel system is too lean or too rich.
I have found that the best thing to do with Mercedes Fuel trim issues is:

if it is a lean code check for vacuum leaks and then it there are no vacuum leaks and both banks are very lean, ( i.e. LTFT is above 15%) it is often the Mass Air Flow sensor
if it is a rich code, it is often a Mass Air Flow Sensor as well
BUT only use the exact part number Mass Air Flow Sensor, DO NOT use an after market Mass Air Flow Sensor!
tuneup fixed mine. Did the tuneup myself, cost $30 bucks in plugs and 3 hrs of my time,