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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Idle Trouble, Code 121

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Old Aug 6, 2004 | 05:04 PM
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mmendell's Avatar
mmendell
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Idle Trouble, Code 121

Newbie to the forum.

I've got a '95 F150 5.8 with 210K miles on it. My idle speed has recently gone extremely high. I pulled a 121 code (Closed throttle voltage higher or lower than expected).

I just spent $1400 on various repairs (mostly front-end) but including the EGR valve. I would like to do this one myself!

Any ideas?

Thanks!
 
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Old Aug 7, 2004 | 12:26 AM
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drewcoolness99
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From: TEXAS!!!!!!!!!!!!
TPS maybe?
 
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Old Aug 7, 2004 | 05:52 AM
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larry derouin
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Agree with Drewcoolness99. TPS
 
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Old Aug 7, 2004 | 08:44 AM
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Is there a way to check this?

Thanks for the input!
 
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Old Aug 7, 2004 | 10:15 AM
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EPNCSU2006
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Yes. You'll need a volt meter to test the tps, but it is a simple check. With the key on (engine off) first probe the orange wire to make sure you have 5V between there and the black wire on the tps connector. Then test the voltage between the green wire and the black wire - at closed throttle, it should be less than 1V, a good reading would be right around .9V. Gradually open the throttle watching the voltage - the voltage should increase smoothly to around 4.8V at wide open throttle. If the voltage jumps around or is outside these ranges, the tps is likely bad (unless there is not 5V on the signal wire).
 
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Old Aug 7, 2004 | 12:00 PM
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I'll give it a try! Thanks!
 
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Old Aug 8, 2004 | 07:11 PM
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That took care of it! Now, a new oxygen sensor, and she'll be back on the road.

Thanks!
 
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