My wife's 03 Vue recently quit running. We took it to the dealership, they said it had a bad cat converter. They wanted 1200$ for a new one. I took it home and cleaned out the converter. It runs fine now, but I get a check engine light. The code is 0421 (Warm Up Catalyst Efficiency Below Threshold(Bank 1)). Is there a way that I can fix this without a 1200$ converter?