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2012 Acura MDX Engine Idle Speed is Erratic or Engine Stalls

The Acura MDX may have issues with the idle air control system, causing:

  • Erratic/bouncing idle
  • Poor fuel mileage
  • Illumination of the check engine light
  • OBD trouble code P0505
  • Engine stalling is possible

The idle air bypass system is made up of vacuum lines, an idle air control valve (IACV), the throttle body, and intake manifold, and allows enough air into the engine to idle when the throttle body is closed. The OBD trouble code P0505 refers you to this system to inspect for failures.

The most likely cause is a dirty or failed IACV, but vacuum lines, intake manifold gasket, throttle body gasket, and IACV gasket should be inspected.

In all cases involving the IACV, the throttle body ports should be cleaned prior to installing the IACV onto the throttle body.

Affected Model Years

This issue affects Acura MDX model years 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, .

24 people reported this problem

  • 2012 10,000 Miles
    When slow down and stop at the intersection waiting to make a turn, the engine shut off, need to press the start button again and the gear will shift to N, need to shift it back to D in order to drive again. When restarting the engine, several warning light turned on. So far, this issue has not been resolved yet.
  • 2012 95,000 Miles
    2009 MDX has stalled 3 times in 10,000 miles. Always when moving. Steering locks up and car difficult to control. Two different repair shops have looked into the problem without resolution.
  • 2012 16,000 Miles
    Engine stalled at highway off ramp after being stopped for about 1 minute. Car shifted into neutral, and completely shut off. Had to return to park, try to restart. Would not do anything. Removed foot from brake, and then reapplied break, pressed button to start again. It started. Drove directly to Acura dealer. They did not find any issues and could not recreate it. Hopefully it doesn't happen again, it was rather scary.

Acura MDX 2012 Common Problems