Join Date: Jul 2003
Location: Arcade, New York
Hmmm, several possibilities. You may have a bad ring on one or more pistons and you are burning oil. Look at your exhaust. When the car is warmed up and it's not real cold out, the exhaust should be clear, not smoky blue. A compression test and inspection of your plugs should tell a tale. Could be a rear main seal on the creankshaft and the oil is entering the transmission area. A bad PCV valve could cause some oil to be consumed but not at the magnatude you are experiencing. You may want to check the transmission fluid level for excessive amount (check while engine is running and warmed up) but that's a little "out there" as far as troubleshooting is concerned. After the car has set for quite a few hours you may want to look at the coolant in the radiator (not the overflow tank) for presence of oil.
You are right as far as the code 0406 (Ehxaust Gas Recurculation Sensor A Circuit High) probably is unrelated, seemingly, to an oil consumption problem. You want to crawl under the car and see if you can spot any areas of excessive oil that may be getting spread around the bottom of the car from windage as you drive. Good luck, and perhaps someone else will come up with some other ideas for you...