Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Exhaust System
HINT: The illustration displays the exhaust system for the XC90.
The exhaust system is made of double-layer sheeting to keep the temperature down. The inner sheet is 1.0 mm thick while the outer is 1.5 mm thick. There is 4-8 mm of space between the sheets.
An exhaust system extends from each cylinder bank. Each side consists of a manifold with close-coupled catalytic converter, pipes, bellows and a rear catalytic converter. Both sides join to form a common pipe after the rear catalytic converter.
The pipes are designed in such a way that the gas flow from the cylinders is not disruptive and there is good flow distribution to the catalytic converters. Bellows in front of the two rear catalytic converters absorb engine movements and compensate for manufacturing and assembly tolerances.
A catalytic converter consists of perforated stones of ceramic or metal (known as substrate). These are coated with a surface enlarger (washcoat) on which the precious metals platinum, palladium and rhodium, the catalysts, are applied.
The catalytic converter has an extra heat shield toward the radiator fan to reduce the temperature.
Four oxygen sensors are used to regulate the engine and monitor the catalytic converter. There is an oxygen sensor upstream and downstream of each close-coupled catalytic converter.
The two banks are almost exactly the same length to ensure good sound. The exhaust system provides the engine's characteristic V8 sound.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.