I recently had a valve job done on my '97 850 GLT Turbo. Fortunately I no longer have a code indicating a miss on #2 cylinder. Unfortunately I now have a Code 0171 which translates as 'Bank 1 system too lean'. After clearing the code the CEL returns after driving 5 miles to more than 50 miles. The only condition I have noticed that seems to affect the distance driven before the CEL returns is the amount of fuel in the tank! The more fuel, the more miles before the CEL returns. What would be the suggestion for curing this condition. The car has 157,000 miles, approximately. The odometer quit a couple of weeks ago! TIA
David

 

Check for vaccum leaks on the engine.
Also check for leaks in the evap. system.