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Q: Bad gas mileage

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Notice bad gas mileage then service engine light came on. Took it to shop where they replace one catalytic converter. Light went off gas mileage still bad. After driving about 1000 miles service engine light comes back on. Only getting about 12 miles to gallon. Car rides fantastic performs well only problem is the gas mileage.

My car has 99000 miles.
My car has an automatic transmission.

A: Hi there. Quite often a damaged catalytic c...

Hi there. Quite often a damaged catalytic converter will mask other mechanical issues that impact fuel economy. One culprit in particular is the EGR valve. The EGR valve works in conjunction with the catalytic converter to help reduce particulate matter emissions coming from the vehicle. Overtime it will become clogged with excessive carbon build-up and can reduce the fuel efficiency of a vehicle by as much as 40% if it’s damaged or dirty.

However, there are other parts on your Infinity that might also be causing your poor fuel economy, which is why I’d recommend having a professional mechanic, such as one from YourMechanic, complete an inspection of your decreased gas mileage. This initial service will allow them to properly inspect the vehicle and determine what’s causing the problem, ensuring the right repairs are made.

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