Instructables

Replacing a Throttle Position Sensor on a Jeep Wrangler

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Picture of Replacing a Throttle Position Sensor on a Jeep Wrangler
It's always best to do any work yourself, then you can be sure it was done right, plus it will save you a considerable amount of cash. If at all possible, I try to do all required minor repairs to any of our out of warranty vehicles. In this case it's our 2003 Jeep Wrangler TJ.

The check engine light came on a couple of weeks ago with the code: PO122 (throttle body sensor/switch) 

Details:

P0122 - Set Condition: Throttle Position Sensor voltage at the PCM is lower than 0.1 of a volt for 1.3 seconds.

POSSIBLE CAUSES
TP SENSOR SWEEP
INTERMITTENT CONDITION
(K7) 5-VOLT SUPPLY CIRCUIT OPEN
(K7) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
TP SENSOR
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO (K4) SENSOR GROUND CIRCUIT
TCM INTERNALLY SHORTED THROTTLE POSITION SIGNAL CIRCUIT
PCM



 
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Step 1: Overview

Picture of Overview
This is a pretty straight forward replacement. I checked around with a few shops in my local area and the price to replace this part was anywhere from $100.00 - $180

Since replacing the TPS I've noticed an increase in MPGs (around a 10-15% increase) as well as better acceleration on hills and while passing.



Step 2: Details, Parts and tools

Picture of Details, Parts and tools
Symptoms: Check engine light is on with an output code of PO122. Engine revs to high RPMs when engine is started. 

Cost: $25.00 - $34.99 (AutoZone and Napa both keep these in stock)

Tools needed: Ratchet set with torx sockets/bits and a strong thumb

Time: 25 minutes

Prep: Disconnect the battery. It's is recommended that you always disconnect the battery when doing any kind of work on the electrical systems of any vehicle. You also might want to wait for your engine to cool down if you have been driving the vehicle recently, unless you like getting burnt.

Step 3: Locating and Identifying the TPS

Picture of Locating and Identifying the TPS
The TPS is held in place by two torx screws and is connected to the vehicles computer by a cream colored modular plug. It is located on the top of the engine next to the air intake.


What brand and size are the tires?

gdhenson (author)  wilson.napoleao.91 month ago

BFG A/T 31 x 15 x 10.5

pricejt442 months ago
I just replaced mine and now my jeep is idling around 250, or stalling any ideas? no new codes coming up.
jmcantu3 months ago

THANK YOU SO MUCH after 3 days of testing my old part i got the new one and still had the same results but after the Clockwise turn then turn back it is now reading infinite resistance ( 0 ) on the meter and is running amazing now hopefully i can smog THANKS Again :)

dbgvette4 months ago

Signed up just to say thanks for this instructional article. About 2 weeks ago, my check engine light came on (2003 Jeep Wrangler Sport). It went off on its own and would come back on periodically. But, it seemed to run just fine, so I didn't put much thought into. Finally, while driving, it came on and I happened to have a few minutes to swing by my local AutoZone to have them pull the engine codes. The code was P0122. The helpful person at AutoZone recommended before spending the money, that I check the connections on the old one first to make sure there was no corrosion or frayed wires that I could fix first. I did a quick inspection without pulling the old one off first (pulled the modular plug, but not the TPS) and didn't find any corrosion or frayed wires. I hooked it back up and went on my way. This afternoon (2 days after inspection), my Jeep started idling very poorly. It would rev to 2000 on start up and then settle back down, but responsiveness was horrible - like trying to start off in third gear. I parked the Jeep and ran back to AutoZone to pick up a new TPS ($30). I replaced the TPS in about 15 minutes using these instructions (except I skipped disconnecting the battery because I forgot). After replacing, the first two starts, the engine would rev to 2000 RPM's and then settle back down around 800. Third start, it just rev'd to about 1200 and now its back to normal (no higher than 1000 on starting and idling around 700). Not sure if I just got lucky by investigating when I did or if checking the plug/wires made it worse. Either way, the problem appears to be resolved. This article probably saved me a good $100 or more by doing it myself. Thanks a ton for the information...much appreciated!

gdhenson (author)  dbgvette4 months ago
Awesome. Glad it worked for you.
shayhurs1 year ago
4 hours--2 working the passenger side bolt out after the TPS developed a crack with vice grips 1/2 turn at a tine with everything shoved out od the way. Needless to say, I also replaced the stripped torx bolts with wrenchable bolts (grin).
Ratfink4u2 years ago
Thanks for the helpful tips! My zip is back when mashing down the pedal and the over revving has quit! 12 mins start to finish!
sdeberge2 years ago
2003 TJ w/ 17,000 miles and TPS problems: intermittent check engine light and the dealer wanted $225 to replace the TPS, so I bought one for $35 and did it myself.

Sent the first TPS back because the motor died unless I kept a foot on the gas, it shifted funny, and revved higher than normal before taking a long time to shift. It had none of these problems with the original TPS, just the occasional engine light.

Second TPS looks like its no good either. First start-up the engine ran at 2000 or so RPMs for a minute, then slowed to normal (the engine was warm). Once I started the test drive the engine died unless I kept my foot on the gas and has the same shifting problems. If I take my foot off the gas slowly, it will keep running but a really low RPMs.

The engine runs fine and there are no shifting problems with the original TPS back in there.

Any suggestions? Some blogs say that OEM is the only replacement part that will work right. Other blogs say you have to disconnect the battery overnight to re-set the engine control module so it will learn the new TPS. I didn't turn it clockwise to set it in place - could skipping that step cause the starting position to be off and result in these problems?
gdhenson (author)  sdeberge2 years ago
Non OEM is fine. That is what I put in mine. The only reason you needed to turn it counter clockwise what to get the metal bit to fit in the slot, if it fit without turning you should be fine. A 5 minute battery disconnect is all you need to reset all of the computer data.

Are you getting any codes or is the check engine light coming on? In the meantime I run this by my buddy that is a local mechanic and see what he says.

Also, I'm a member of a Jeep group here in St Louis that is a wonderful source of information. Everyone of the message boards are helpful and we have numerous mechanics in the group.

http://www.midwestjeepthing.com/

I have a 2004 Wrangler that I bought 8/18/11. Daddy replaced the TPS 2 wks after I got it. Having issues again, but this time I will be replacing w/your assistance! Thanks for posting the instructions!
gdhenson (author)  melissaalexander2 years ago
Feel free to ask if you have any questions. I've owned Jeeps since the 80s, I might be able to help you
Not only do I have the same model and year Jeep, I also have the same issues you describe here (RPM's race, pain to pass someone on a hill, idiot light keeps coming on). I have asked friends and mechanics on this issue, and no one has been able to figure it out. One shop told me that I would have to do a few hundred $$$ worth of work. Now, thanks to you, I have a better idea of what to do and where to look. Awesome.
gdhenson (author)  atombomb19454 years ago
Very cool - I hope this helps. Feel free to post any questions you might have. I'll be replacing the A/C blower resistor this weekend and will post a new instructable for that. I also have the photos for adding new sway-bar linkage, I'm working on the instructable for that today.