Can anyone give me insight on this again. I've got a 2000 s80 T6 100k miles with the CEL on. It was throwing code P0432 showing the low efficiency on the Cat(bank 2). Now its throwing both P0422 and P0432(Bank 1 and 2). My scanner shows Short term and Long term fuel trims to be normal (STFT +/-10, LTFT 0-2.5) and as far as I have read that should mean no vacuum leak as well as no injector problem?
The only reading I can get on my scanner for 02 sensors is the rear which appear to be stable at .440v.

If I backwards reference to a volvo code ECM4801 and ECM4901 the fault tracing is check for Intake Leak, Exhaust Leak and Fuel pressure. If none of that works it says replace the CAT but it says nothing in fault tracing about o2 sensors.

It also says under DTC information; substitute value - rear o2sensor control is disabled. Which I don't understand.

I've purchased new o2 sensors for the front and back because I figured, 1: If I do have to change the CAT I should put in new o2 sensors anyways and 2: With 100k miles on the car it wouldn't hurt to change them.

So my plan is to drop the CAT out, have a look inside to see if I can see anything obvious, change the o2 sensors and hope this works. Even though according to the fault tracing this should not be part of the problem.

Any input is greatly appreciated. Thanks

 

It is rarely ever a bad cat.
So either there is a vacuum leak or the O2's are bad.

 

Thanks Tech! In your opinion do good STFT and LTFT numbers negate a possible vacuum leak or not really?

 

Not sure about those Volvo's system reads a little different. at 1.0 it kicks the long term fuel trim in. Anything under 1.0 is good.
Your looks like it reads differently.

 

You can test the converters with an IR temp gun. They should be about 100 degrees hoter at the inlet if they are doing their job. The number one killer of converters is raw fuel. If there is something wrong in the motor, ie. missfire, plug too old. O2 sensor, weak coil pack etc.. the motor is not burning all of the fuel sent to the cylinders and the fuel goes into the converters and erodes the precious metals causing failures.

 

Correction They should be hoter at the outlet.