It started with P0430, which refers to rear upper oxygen sensor.
We replaced with a Bosch unit, then started getting continual P0132 and P0152 codes.
I finally decided to visit our local Jag repair shop, since smog deadline is imminent.
“For the x300, these two codes mean oxygen sensor issues.”
On other models, it means cats are bad.
They only use NTK or NGK units.
I bought 2 NTK 25018 for the upper sensors –
200 miles of driving around, and today - PASSED SMOG !!
Of course, I also had new oil, new plugs, new air cleaner, fresh gas, crossed fingers…
In California, smog certification problems can be the death knell of many a car.