2016 stubborn malibu

[George_San_Jose1]

The p015b code is saying the pre-cat o2 sensor’s output signal is taking longer than expected to respond to a lean to rich transition. Figure out where that O2 sensor is located (it will be between the exhaust manifold and the cat), and carefully inspect the wiring harness and connector for corrosion, burned insulation etc. If nothing found you’ll have to go to a shop where they’ll use a scanner to monitor the output signals as they bump the accelerator. I’d do both those first before considering to replace the O2 sensor. Unless there’s some reason to believe the O2 sensor is faulty of course. O2 sensors are usually pretty robust. One problem that can cause this is if some contaminant like oil gets on them, outside the exhaust stream. So take a look for that while you’ll checking the wiring. O2 sensors must have a small opening from inside the exhaust to outside the exhaust for them to work correctly.