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Matt
Matt, Mechanical Engineer
Category: Mazda
Satisfied Customers: 21851
Experience:  BEng hons Mech engineering, in auto industry 22 years
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2009 Mazda 3 with P2096. Runs fine, using 95 fuel, new rear 02 sensor but code came back

Customer Question

2009 Mazda 3 with P2096.
Runs fine, using 95 fuel, new rear 02 sensor but code came back after a day
Submitted: 1 year ago.
Category: Mazda
Expert:  Matt replied 1 year ago.
Hello I'd next check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate. this can lead to catalyst failure as the extra fuel can re-light inside and melt the catalyst The best way to find an exhaust leak is to run the engine from cold and feel around the exhaust joints with your bare hands - you'll have about 30 seconds before it all gets too hot and you should feel any escaping gas blowing over your fingers