Low idle, 411 and 412 codes KOER | Ford Explorer - Ford Ranger Forums - Serious Explorations

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Low idle, 411 and 412 codes KOER

Will Presley

New Member
October 4, 2009
Reaction score
City, State
Memphis/Nashville, TN
Year, Model & Trim Level
1994 Eddie Bauer 4x4
Hey, folks! I have '94 Eddie Bauer 4x4, 4.0L OHV. I recently fixed a bunch of air intake issues that were causing a lean condition. The truck ran great for a while, but now it's running rough again. I did an idle relearn procedure, which helped for about a day. Now the truck is running with a slightly low idle, and it's running rough. No check engine light, but I did the self test and passed KOEO, though I got codes 411 and 412 for KOER. I've checked for vacuum leaks and can't find any. I've replaced the IAC about 5 times, so I doubt that's the problem. Any ideas? Thanks!


Smokey the clutch is; Missed shift you did
Elite Explorer
Moderator Emeritus
October 5, 2008
Reaction score
Humid, Damp, and Hot
City, State
Houston, TX
Year, Model & Trim Level
'98 EB, '93 Limited
Clean out the throttle body. Your IAC may be working, but if the passages are clogged, it really can't do much.


Well-Known Member
April 28, 2015
Reaction score
City, State
Pensacola FL
Year, Model & Trim Level
1994 Explorer Sport
Seconded! While you are at it pull the EGR Valve and ream out the passage behind it, It actually is about 1/2 inch in diameter.