Code 21 ECT

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Dec 18, 2015 | 10:13 PM

wtroger

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Cargo Master

Joined: May 2001

Posts: 3,208

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Code 21 ECT

Wanted to pass this on. My 1989 f-superduty 460 5 sp. recently wouldn't idle down. Wanted to idle at 1500-2000 rpm. check for vacuum leaks none found. Tested IAC and it passed. It finally got where it wouldn't run unless really wound up. If it died I had to start it like it was flooded and it was. Finally crippled it home. Ran the codes got a 21 a 33 and 87. the 21 ect out of self test range 33 no egr movement that ones been there a long time 87 primary fuel pump circuit failure. That couldn't be true it was suffering from to much fuel. Replace the ECT and everything was back to normal. Idles at 900 rpm runs fine. I would have never though that a coolant temp sensor could cause an engine to run this poorly.So just an FYI for others.