A friends 99 f150 4.2 Ltr. v6. Check engine light on, went to advance auto, scan tool said left bank front o2 sensor code po130 iirc. He replaced the sensor, a few days later light on again (he had the code cleared after repair.) It all happened after an oil change at the dealer. Any ideas? What should I be checking for. I read somewhere maybe the air inlet tube is open? I will have to check it when he brings it over later. Thanks.

 

A code NEVER means to blindly replace any part; even if that part is mentioned in the code definition. The code tells you where to START your diagnosis. Look at it this way: if your speedometer showed 10% slow, would you replace the VSS?

Post the text from the code definition (from several sources if possible) and think about what it actually says.