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Q: O2 sensor or converter, ECM, or harness?

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Two O2 sensors are bad in the codes also saying low flow. The engine has a very rough idle once started to the point of stalling. Once it's moving it really runs quite well with almost no noticeable problem. Only at idol us it noticeable and very noticeable it is.

My car has 159000 miles.
My car has an automatic transmission.

A: As you may know the oxygen sensors which ar...

As you may know the oxygen sensors which are part of your emissions system read exhaust gases to determine whether or not the appropriate amount of oxygen is present in the exhaust. Based upon this information, the ECU then makes fuel adjustments to the engine. Too much oxygen may be present in the exhaust gas due to things like an exhaust leak, a vacuum leak, a faulty mass air flow sensor (causing a lean fuel condition) or faulty fuel injectors. To little oxygen may be present in the exhaust gas may be caused by things like a clogged air filter, a failing mass air flow sensor (causing too much fuel to be introduced to the motor), bad fuel injectors or a clogged catalytic converter. I would suggest having an expert from YourMechanic come to your home to diagnose your emissions system.

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