Hi. I own a 2001 Mitsu Diamante. I went to Autozone and they read out P0154 and P0174 trouble codes, which indicate:
O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1), and
System too Lean (Bank 2).
I saw an article on the web that suggested that this could be caused by a clogged fuel injector. I added high strength fuel injector cleaner on two occasions back to back, reset the CEL light and after a couple of days the problem came back. Any other suggestions or insights? Thanks in advance.
Dave

 

Take it to get a fuel system cleaning. The off the shelf Injector cleaners are not really worth thier wieght in gold.