Hello everyone My xc90 2012 3.2 is probably in a situation where it produces a mixture that is too lean or too rich (not sure which of them) and this causes too much heat to be generated in the converter, which probably damages it in the end. What could be the reason? The oxygen sensors are new from Denso and just to be sure I changed to used original ones to see if it has an effect. The maf shows at 2000 rpm in idle about 13g/s - I think that should be normal for checking on Google.
Does anyone have any other suggestions on what parts/components can affect the fuel mixture?

 

What CEL fault codes are you seeing? Possible causes for a fuel mix issue include intake air leaks, exhaust leaks, fuel pressure, sensor issues (MAF, MAP, ECT ), front O2 sensor, intake air constriction, exhaust constriction, intake air temp (ie preheat stays on). I'd say the first step is to check for fault codes as they should tell you if you whether there's a sensor reporting out of range and whether you are running lean or rich. If as you noted, you suspect there's too much heat going into the cat, that suggests to me a lean condition. Lean can be caused by low fuel pressure, injector issues or too much air. Also keep in mind, your O2 sensor does its work when the engine is at speed to adjust the run time fuel trim vs the idle fuel mix. Does your OBD2 reader allow you to capture real time data when driving to determine what the O2 sensor is doing?

 

Yes
What should i look for?

 

first scan for codes. If you've already cleared them, it may take a few hundred miles of driving for the codes to reset. As to the real time data, you probably have to google around to see what the specs are for fuel trim (ie O2 sensor duty cycle). Given your car is a 2012, if you don't want to engage a dealer or Volvo tech who already has VIDA/DICE you may be able to score the 2014 VIDA CD and DICE adaptor on eBay. Probably cheaper to just pay the dealer for a diagnostics fee (usually one hour).