Q: Car starts but keeps shutting off when I apply brakes or slow down

asked by on October 10, 2016

Cat had engine light on, I patched up a hole on the exhaust pipe, I was losing power and using up more fuel then normal. Car now sounds much better and runs smoother but I notice it now keeps shutting off when I ease off the gas. It starts right up but continues to shut off when letting off the gas pedal. I was told my catalytic converter might be clogged and causing the car to keep shutting off. I really don't know what to do, I think the codes read, mass air flow sensor, had it replaced, engine light went off but car still shutting off

My car has 236000 miles.
My car has an automatic transmission.

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Hi, thanks for writing in. Having the precise codes is very important-- even if the Check Engine is no longer illuminated. There can be transient codes that have not yet set off the light. The idle air control valve and throttle body may need cleaning. With your mileage clogged fuel filter and dirty/leaking injectors are something to check as well. A clogged catalytic converter is a possibility-- that would be most apparent by an inability to build up speed, or take on hills where more power is required. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

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