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Malfunction Indicator Light (p0121)

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mil p0121 tps
2K views 1 reply 2 participants last post by  binnsmark 
#1 ·
Hey all,

I'm just gonna start by saying I don't know much about engines. With that being said, I took to JeepForum.com and google.

My Jeep is a 01' Jeep Wrangler 4.0L. So here's my problem. Driving around I've noticed my Jeep will occasionally idle a little bit higher than normal. It makes a noticeable difference when I drive. I can feel it in the clutch when I try to shift. I can make it drop to normal idling RPMs if I tap the accelerator. This always happens when the A/C is on.

So when my "Malfunction Indicator Light" lit up, I looked it up. I found something that said a code is associated with this light, so I did the "on, off, on, off, on" trick and my odometer screen read P 0121. I looked this code up and it sounds like it has to do with the Throttle Position Sensor (TPS) and wiring. I jumped under the hood and wiggled around the wires connecting. I found the next morning that the MIL turned off and it drove fine, so I wanted to see what the A/C did... Same thing happened, next time I turned my Jeep on, the light was back on.

Every parts store and auto shop I've talked to says the diagnosis requires special scanners which will cost for diagnosis. Has anyone had this problem or know of some tricks I can try to get a better idea? My personal (ignorant) opinion is the TPS is bad or dirty. But I am concerned because of the issues associated with the A/C.

Thanks for reading and I appreciate the help!
 
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