fault code 0172, system too rich bank 1

[twilightflyer]

can anyone let me know what to look for in rectifying this error code.I have changed the engine coolant sensor and the MAF sensor,but no difference.
regards

[jtz54]

I got this code when a hose broke going to the idle air control valve broke.
Other symptoms included bad idle at first start and lack of turbo boost.
Fixing the hose fixed all the problems.