when do you need to recalibrate the computer after service?
When just replacing the exhaust, I don't see a need to reset the computer, but if you changed 02 sensor and did the major work, maybe it would be a good idea. Disconnect the negative battery cable for 20mins and then reattach. The PCM will be reset with default settings and your good to go.
you don't. just clear the codes ,if they come back you still have a problem.
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