A lot of advices point to the EGR valve.
According to my mechanic, only the California model has EGR valve.
I have changed spark plugs and the rear oxygen sensor.The check engine light still come on.
Answeri believe that this car has a mass airflow sensor located between the air filter box and the throttle body. it has a plug with maybe 5 wires on it and is held in place by 2 Phillips head screws. a code po171 is almost always fixed by replacing this sensor. the misfire code will also go away as problems with this sensor can also cause misfires. clear the codes after replacing it and i can almost guarantee they wont come back!The 2014 Toyota Avalon has a V6 engine.
The 2012 Toyota Avalon has a V6 engine.
The 2005 Toyota Avalon has a V6 engine.
The 2008 Toyota Avalon has a V6 engine.
The 2003 Toyota Avalon has a V6 engine.
The 2009 Toyota Avalon has a V6 engine.
The 2004 Toyota Avalon has a V6 engine.
The 2001 Toyota Avalon has a V6 engine.
The 2013 Toyota Avalon has a V6 engine.
The 2010 Toyota Avalon has a V6 engine.
The 2011 Toyota Avalon has a V6 engine.
The 2006 Toyota Avalon has a V6 engine.