BMW of North America said it is voluntarily recalling about 156,137 2010-2012 model-year vehicles in the United States because of a potential defect with the variable camshaft timing.

BMW says the recall will address a problem with the variable camshaft timing, also known as VANOS, which could reduce engine power and further cause damage if not repaired.

“The unit rotates the intake or exhaust camshaft in order to alter the timing of the lift of the respective intake or exhaust valves,” a BMW spokesman said for Automotive News.

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In a statement, BMW said that “in very rare cases, the bolts holding the variable camshaft timing unit housing may become loose or, in extreme cases, break.”

Should that happen, the “check engine” or “service engine soon” light comes on followed by the display of a “check control message.”

“If ignored, the problem can become progressively worse, eventually leading to no start conditions, stalling and engine damage,” BMW said.

The affected models are:

• 2010-12 1 series

• 2010-12 3 series

• 2010-2012 5 series

• 2010-12 5 series Gran Turismo

• 2012 6 series

• 2010-2012 X3

• 2010-12 X5

• 2010-12 X6

• 2010-12 Z4