I took my vehicle to my mechanic for inspection check up. My mechanic told me and supplied paperwork from their scans that the P0420 sensor in the cat converter was shot again (3x in 5 years) and needed to be replaced. The engine light had come on 3 weeks beforehand and I had it read and knew what it was. They sent me to Hyundai dealer as it was under warranty with documentation. I get to Hyundai dealer tell them it needs the sensor for inspection and an investigation for oil leaking from back of the engine. I also told them I was adding 2-3 quarts of oil between oil changes. They told me my mechanic over filled oil by .5 quarts and that’s why the engine leaked. They investigated after I disputed by saying an oil change had been performed the day I brought it to them and found a bad head gasket, fuel pump seal, and oil pan seal. They charged my extended warranty for those repairs, shut off engine light for cat converter sensor without replacing it, and made me do an oil consumption test of 1000 miles. Car was still not inspected at this point. After 35 miles check engine light comes back on. Cat converter sensor P0420. I take it back in. They tell me they won’t replace it until the oil consumption test is done because they need to know if oil is coming through the exhaust pipes (it was). I complete the test and go in. They tell me engine is burning .5 quarts of oil/1000 miles which is acceptable and as long as I complete oil changes every 5000 miles I will be fine. They then tell me if I want sensor replaced I’m 800 miles over warranty so I have to pay $2400 to replace. Called corporate they’re only willing to cover half the repair as ‘good will’ for the cat converter and was quoted $1300 by the dealer in question. Almost a month and still not fixed and still can’t get car inspected because the check engine light is tripped by the P0420 sensor in the cat converter. It’s the only vehicle my family has. I’m forced to pay to have transportation.