Hi.. My XJR will not pass annual control because of high (9.5) co readings on both the exhausts. Engine is performing well throughout the rev range only burning too much petrol. Sensor on top of thermostat house is ok and air meter works ok. Will the two Lamda sensors or the catalizers maybe be faulty? Will the lamdas be equal,only plugged in at the right order? Car has done 166000km.
If someone can answer what might be wrong,please let me know.

Regards
Arnstein

 

My 1995 XJR6 has the same symptoms. My mileage is almost the same as yours, but Rose has undergone many operations to awake from deep sleep for three years, and got new O2 sensors, new headers, new injectors, CPS and new ECU, so she is awaiting re-adaptation of the O2 sensor and the Throttle Position Sensor with the new ECU before re-evaluating the numbers and tackling any recurring issues, including high CO and high idle.

If you have no recent change in parts, it could possibly be the O2 sensors, MAF sensor, temperature sensor (engine) and air temperature sensor (on the supercharger), and/or the catalytic converters on the way out, thus feeding the ECU with inaccurate data?

 

I could not pass the Emission test in Ontario Canada high CO reading. Faulty injector replaced, and then dead 02 sensors and Catalytic converts. replaced both and sailed right through Etest.
Snowball