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Q: codes P0021 P0011 keep coming up sometimes reader says pass but two monitors not on 2006 Hyundai Sonata

cars runs good oil light comes on with idle after warm- oxygen sensors changed- new oil - new oil control valves
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Test actual oil pressure using manual test guage kit ... Suspect low oil pressure.... Possibly from engine sludge. .. Likely due to infrequent engine service/poor quality engine oil and oil filter.
That should be enough oil pressure **with engine idling at normal operating temperature** .. However at this point vehicle presence is required for 'systematic' hands-on testing .. Too many details easily get lost in transition over the Internet! .. (**)
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