Just had my 2007 xj8 emissions tested yesterday, It passed ok but on the inspection sheet it shows Oxygen Sensor,,,,,,Not Ready,,
the mechanic say we can have one item show not ready and still pass, I had the same comment two years ago on its last test, the car starts good, runs good, good gas mileage , just wondering if i have a faulty oxygen sensor, i have a very basic obd code reader so that doesn't give me any details, would appreciate any thoughts,
regards
Dave,
2007 xj8 90,000 miles,

 

What is the DTC stored in the system? Is the code pending?

 

Hi there are no codes stored or pending there are a list of systems monitored, all of them show ready except for the oxygen sensor which show not ready,

 

The emissions system readiness monitors should all reset with sufficient drivetime unless something is not performing fully within specification. With an inexpensive ELM327 OBDII adapter (less than $10 on eBay) and the Torque Pro app on your Android phone ($5 from the Google Play store) or an equivalent solution for an iPhone, you can check the Mode $06 data to see which oxygen sensor (O2S) monitor is not resetting, and you can then use live data to observe the behavior of that O2S to see how it corresponds to the behavoir of the other upstream or downstream O2S. You may see the clue there.

Another clue may be found in the Short Term- and Long Term Fuel Trims (STFT & LTFT), which will tell you if the engine is running lean or rich or if one of the O2S mistakenly believes that it is.

The first document I am attaching explains the On Board Monitoring system and the various monitors.

The second document gives Drive Cycle procedures to complete each of the monitors.

Cheers,

Don