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Recently, I had my catalytic converter replaced because my car was consuming 40% - 50% or more gasoline than it normally uses. I own a 2003 Toyota Celica GT that has a 1.8 liter engine with 4 cylinders, but it seems like it might be running more like an 8 cylinder car. The catalytic converter did not help the gas consumption at all. I even tried pouring several bottles of fuel injector fluid into my fuel tank, but they did not help at all, either. I think that I might need a new muffler (It made a loud noise for a while after I hit a big pothole) and/or an oxygen sensor. What do you think that I should do to fix that problem?

Answers from the Automotive Experts

Amanda J. Pierce, MBA Terri I do not see a muffler issue causing such high fuel consumption. Have you traced your fuel lines to insure you don*t have a pin leak after impacting that pothole?

Audra Fordin, Owner at Great Bear Auto Shop Hi Terri, I am wondering... was your engine light on and that was why you changed your catalytic converter? Catalytic converters do not go bad on their own, rather they the destroyed by the component that is in need of replacement. Yes, typically it is the oxygen sensor that does this damage BUT, if your engine light has not come on I would doubt this is the cause of the trouble. More important, not to guess. You need to have your car checked. If you are loosing as much gas as you are saying, this is not going to be too difficult a problem to solve. Good luck. Mechanically yours, Audra

Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube The converter and the muffler have nothing to do with gasoline. See a good mechanic to diagnose the problem.

Diane Larson, Owner/Manager at Larson's Service Hi Terri, I am so glad you wrote in about your problem The catalytic converter may have been damaged from the excessive fuel consumption, BUT it was not the cause of the fuel problem..... You need to have the vehicle tested to find the cause....which may be a bad sensor, fuel delivery problem, vacuum leak or ? Please take your vehicle to a shop who can properly test the system soon, before the new catalytic converters are damaged...... Have a Fun Day!

Laurie Sarno, Co-Owner at Super Girls Auto Hello Terri The only thing a catalytic converter does is reduce tailpipe emissions. A plugged converter can cause fuel economy issues, but will almost always be accompanied by a serious loss in engine performance, especially at higher RPMs. More than likely, the poor fuel economy issues are caused by a bad MAF (Mass Air Flow) sensor, Throttle Position sensor, or O2 sensor, commonly referred to as an oxygen sensor. Note that if your vehicle has less than 80,000 miles, it may be covered under the factory emissions warranty which is required of all manufacturers under EPA regulations. Hope this helps. Super Girls Auto

Lori Johnson, Owner and Instructor at Ladies Start Your Engines Dear Terri, Catalytic converters really only go bad when raw gas flows in and burns up the inside of the converter. I would suggest that you have your fuel system checked for leaking or bad injectors. If there was a problem with the O2 sensor, you would get a check engine light. It*s important to make sure that raw gas is not burning in your converter or you*ll be replacing it again. If you want to clean the injectors I would suggest having a technician do it through the injector line itself. I haven*t found that the additives do the job as well. As for the muffler, check to see if it has any holes. You*ll need to replace it if it does. Most likely your muffler is not the problem for your excessive fuel consumption. Lori Johnson

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