2012 Acura MDX Owner's Manual - Page 144

Keys and Locks Retractable Master Key RELEASE BUTTON Push Always use the fully-extended key when you insert it to the ignition switch. If the key does not fully extend, the immobilizer system may not operate properly and may prevent the engine from starting. The key may come in contact with your finger while being retracted or extended. Make sure your fingers do not touch the pivot of the key when retracting or extending the key. Instruments and Controls The master key can be retracted into the remote transmitter. To use the key, push the release button to release the key from the transmitter. The key should be fully extended. To retract the key, push the release button and at the same time push the key into the remote transmitter until it is securely latched. 137