I have a 2001 Chevy Impala LS 3800 V-6. 3 mos. ago check engine light came on and read catylitic converter shot. Replaced it. Check engine light came on again-Bank 2 o2 sensor. Replaced it. Check engine light on again Bank1 02 sensor. Replaced it. Now every 1500 miles check engine light comes on and indicates bank1 02 sensor. I have cleared codes several times. and every 1500 miles check engine light comes on. Read code and bank 1 02 sensor code. This is the best performing car I have owned gets 30 to 32 MPG highway consistently. It has 160,000 miles on it. My question is. Does the computer need to be reflashed by a chevy dealer to clear the codes properly? I have been driving this way for months and performance is not the problem. It will become a problem when I get it annual inspection in the state of Texas. Thanks for your help. I used a handheld computer code reader each time to reset and clear codes.