One problem related to engine has been reported for the 2009 Toyota Scion Xb. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Toyota Scion Xb based on all problems reported for the 2009 Scion Xb.
The engine oil filter adapter does not provide sufficient threads to safely retain the oil filter on the engine imo. The filter on my xb was held on by 2 1/2 threads after it was tightened by 3/4 of a turn. Because of the way the engine housing and filter adapter are machined, the amount of protruding threads that the filter can be assembled onto is uncontrolled and there may be cases where the filter will pop-off while the engine is running, dumping all the oil from the engine. Here are some fixes; (for existing engines) unscrew the adapter so that the filter can be turned on with 4-5 turns before the seal contacts the mating surface and stake it in place. (for future design) provide a positive stop in the housing or adapter so that the correct protrusion of the adapter threads are obtained. Issue was found and fixed by me without the filter coming off in service, but it did concern me enough to fill out this complaint. This issue may apply to other Toyota vehicles with the 2. 4l i4 engine.