If your Volvo XC90 exhaust smells like rotten eggs out the tailpipe it time to take notice, figure it out and get the problem resolved. Because a) it is a problem and b) it needs to be resolved because it can be (or be the start of) a serious issue with your SUV. I’ve seen it a few times now in various forums. XC90 owners complaining of a foul sulfur smell coming from their Volvo.
Chemically, it’s just a matter of the hydrogen sulfide (which smells) in your gasoline not being converted into sulfur dioxide (which is odorless) before it exits your exhaust. The sulfur is converted into sulfur dioxide by your catalytic converter (go figure, right?) so if you’re getting the smell of rotten eggs from your exhaust, that is definitely one place to look.
Suspect #1: Your catalytic converter.
It’s possible that your catalytic converter may have an internal issue. Sometimes, the small filtering screens get worn and don’t do their job the way they should, allowing the smelly fumes to slip past and into the outside air. It could also be that the filtering layers have just worn out and are unable to do their job effectively.
There’s no “fix” if this is the issue – you’ll simply have to buy a new catalytic converter. Otherwise, you’ll also likely fail emissions testing and be faced with the stress of being told your car registration can’t be renewed because your XC90 exhaust smells – and it’s polluting too much.
Keep in mind, there is a section of exhaust prior to the catalytic converter. If there’s a hole in this section, some of the unconverted exhaust will escape and cause the smell. So if you only smell it at the front of the XC90, or if it’s stronger, at the front of the car than it is at the rear, consider inspecting that section of exhaust.
Suspect #2: Your engine is running too hot.
However, it’s not the only place to look for the cause of the smell. Catalytic converters are not cheap, so it makes sense to have the issue investigated to determine that it’s the actual cause. Another culprit is an engine that runs too hot. The XC90 (and many other Volvos are known for their ‘dead reckoning’ when it comes to the coolant temperature gauge. So if yours is reading a little past center, have it looked at. You may need a coolant flush, a thermostat or both. Or there could be something else causing your engine to run on the hot side.
Suspect #3: Your fuel flow.
Lastly, it’s always a good idea to change your fuel filter to ensure your engine gets the right amount of filtered fuel to the cylinders – at the right pressure. A dirty fuel filter causes fuel that is improperly filtered to make its way to the engine at an improper pressure, causing problems that can lead to the sulfur smell.
If your XC90 exhaust smells, get it looked at. You can easily change the fuel filter yourself, but the other possible culprits should likely be handled by a pro to ensure you’re not wasting money on a catalytic converter you don’t need, or on other repairs that won’t solve the problem.