The oil usage definitely seems to be on the high side, and it certainly isn’t helping the situation with the catalytic converter
Assuming the catalytic converter truly isn’t doing its job anymore . . . there are other possibilities for that code you got . . . the oil usage was probably a factor, along with the age
At 12yrs and 140K, it wouldn’t be unheard of to need the converter replaced, regardless of oil usage
A decent mechanic should be able to determine if the converter truly is the cause of the code, or maybe it’s something else, such as an oxygen sensor or an exhaust leak.
Would the warranty cover emissions and/or exhaust components, such as the catalytic converter?
If not, there are plenty of exhaust shops that will happily weld in an aftermarket catalytic converter, for a modest price.
As for oil usage, if you check that oil level weekly, and add as needed, the engine may last a good long while.
Do you live in a state with emissions inspections?
While personally I think a quart every 2,000 miles is high because none of my vehicles lose an appreciable amount of oil at all, there are new cars that consume that much, and it’s a real uphill battle to get it fixed under warranty even if the car’s only a few months old.
That said, that slow of an oil burn probably isn’t going to do anything bad to the catalytic converter.
You’re going to have to get the car looked at to see why it’s throwing the cat code. Report back with the findings.
If you haven’t changed the oil in the last year and 7,000+ miles, then you have likely voided any warranty you had when you bought the car. Sorry to say that, but it is very likely the case. Find a decent mechanic, get the oil changed, and a vehicle diagnosis. Go from there.
“In the year I’ve had it twice has the low engine oil light came on.”
Some questions have been asked to determine exactly what that statement means. Cars’ oil is monitored in terms of : volume (sufficient amount) and pressure ( one measure of engine “health”).
Oil Volume
I looked it up in my Bonneville Manual. The “CHECK OIL LEVEL” message comes on when the oil is at least a quart low. I assume this is the message you received and acted on by adding oil.
Oil Pressure
Your Bonneville has an Oil Pressure gauge to the left of the speedometer. It has a needle that moves with changing pressure. It indicates pressure in a range of 0 to 120. The oil pressure changes with engine speed and temperature. There is a section on this gauge marked with a red line (pressure too low when engine is running).
Do this.
Next time you start the car, while in Park, running, but before driving off (engine “cold”), note the oil pressure.
Then after driving, but in Park while still running (“engine warm”), note the oil pressure.
It shouldn’t be in the red zone on the gauge. Post the readings here if you’d like and we can help interpret what the gauge is saying about engine health. CSA