[Mark]

As far as I know once the codes are cleared they’re gone unless they trigger again after driving. Some might first reappear as a “pending” code before triggering a SES light. One way to know if a car recently had its codes cleared is to verify the emission ready tests used for state inspections. Many of those codes may still read as incomplete; however depending on the age of the vehicle, certain scanners will show some of the more advanced test as being incomplete perpetually because the vehicle doesn’t perform that test. I believe a good one to look for is the down stream or secondary O2 emmision ready test.

[Mark]

Thank for the reply. The illustrations provided look to be for the passenger (differential) side and not the driver side. Passenger side is way more pia than driver side; however driver side would still require about two to three hours of work for me. I’m trying to find out if this is a sign of failure or not.

[Author]

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