Random o2 Sensor Codes p1117 p1121 Just Replaced too

[porscherescuer]

Hi everyone,

New to the forum and what a way to start. I have a 99 boxster with 95k miles. I've been getting codes for o2 sensors for several months now. I had p1117, p1121, p1124 and p1126. I also had P0446 one time I checked the codes which I guess is a purge valve? I started by replacing all o2 sensors and the mass air flow. p1117 and p1121 came back within 15 minutes of driving and the others came back within the second or third drive cycle. I cleared all the codes two days ago to see what it was currently showing. So, after about 200 miles, a big bottle of gumout and some spirited driving over the past few days I (just) have p1117 and p1121. I am taking it to my mechanic tomorrow, which is 200 miles away, but he's good and cheap. Where do we start? Checking the 02 sensor values? If so what should the range be? Checking wiring from sensors and trace it to dme? Has anyone seen this before? Thank you in advance for any insight or diagrams which may lead to a cure.

[RFM]

P1117/1121 refer to the sensor heating, i would check that first. It could be something simple as a bad connection or a short in the wiring, but also a faulty sensor. Use a diagram with the pin # to make it easier.

[porscherescuer]

I checked the driver side post cat 02 and it was toast. So apparently when the shop said they replaced them they must've forgotten one. Changed it out and after driving it 500 miles since yesterday there is no CEL!! I averaged around 30 mpg and the vehicle seems to run smoother now as well.