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Q: How to fix or figure out exhaust system leak code P0402

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The engine EGR system may have exhaust leaks at the back pressure transducer

My car has 133500 miles.
My car has an automatic transmission.

Hi there. The code you have denotes excessive EGR flow detected, not exhaust leaks. Anything on the EGR system could be causing this - a stuck open EGR valve, a stuck open switching valve/transducer, debris caught in the EGR diaphragm. Performing tests on this system should be performed by a qualified technician to ensure a proper diagnosis of the system and prevent the return of a Check Engine Light or drivability concerns. YourMechanic has several available technicians that can assist you with a Check Engine Light diagnostic if you would like to have an expert pinpoint the problem and guide you through repairs on site.

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