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Q: code po303...what would I expect the o2 sensor to read if an injector is leaking on 1999 Buick LeSabre

the reader picks up a po303 only after a long period of idling.the first o2 sensor reads .1 to .7.
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This code indicates a misfire on # 3 cylinder! Possible ignition fire, fuel injector or low compression. Forget about anything else until this is repaired!!
new wires, plugs. ohms correct in wires...plugs gapped @ .065 haven't checked compression
here's where the problems spark plugs and wires. compression good, new coil, had a scan run and was assured that the injector was bad, replaced injector..PO303 still comes on at idle. I wiggled the wire at #3 injector and that seemed to work. I soldered in a new #3 injector plug in and wire. latest result is.....PO303
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