Before O2 Replace, Check Volvo Elbows
Thanks to the anonymous denizen of bay 13, there’s a new scheduled maintenance item for our T5’s. There is a vacuum hose at the top front of the engine that sneaks under the fuel rail. At the top end, there’s an elbow that rots out pretty quickly, letting false air into the hose. This can trigger O2 sensor problems. WAIT, there’s another. Lean over the engine (on the driver’s side) and from the top of the engine (almost right under the top engine brace) there’s another identical elbow that is probably rotted out. Go to the Volvo place and purchase both elbows (about $3 Cdn each), install them, clear your codes and you just might find the O2 problem gone.
Better to spend the $6 rather than the $500 (for the O2 sensor parts alone). While you’re there, you might see the rubber donut thingee in the top engine mount is snapped. It isn’t dangerous, but can cause some engine movement and subtle noises. Easy to replace, about $30 Cdn from Volvo.