Help p0123 Revs all over

[twack]

So tonight i had a 2 hour drive in a Crazy thunderstorm. I noticed while driving my coolant guage would drop, sometimes all the way to cold and then go half way and back usually staying at half way. as i was about 2 miles from my house i feel my revs changing, it would drop then go high thengo low, just sketchy as all get out. The check engine light came on when the revs started acting up. i pulled the code and its p0123 and thats the only code other then an old 4wd switch error. whats going on you guys think?

 

[LibertyTC]

Po123 is (TPS) throttle position sensor Circuit high.
Remove both the TPS and IAC (intake air control)
Give them a good cleaning with spray throttle body cleaner, and the ports inside once they are out, as tons of carbon builds up in there. Try that before replacing the TPS.

 

[twack]

thanks ill try that and get back to you guys, even though a tps is only $35

 

[LibertyTC]

Twack- T-20 torx bit in a 1/4 ratchet assembly is best to remove them. Note on IAC & TPS Mark the side from housing to unit base, makes easier to remember angle to re-install.
Use can of compressed air or other air to units and ports after cleaning, to dry and remove any left over dirt.
ON TPS unit as there is a metal prong or tab inside that has to be aligned into a slot when re-installing.
You will see what I mean once you have it out. (EASY JOB)
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Be sure to clean both of them IAC & TPS your idle will Thank You.
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[Jmoo27]

just got done cleaning mine, started it up and the idle went from 1100 down to the normal 600RPM! the code hasn't cleared yet but ill drive around and see if it goes away!

 

[ocifersven]

So far, so good

I looked everywhere on Google for an answer for my sporadic revving problems on my 2004 Jeep Liberty Limited 3.7L 2WD. I'd be on the freeway and my car would downshift at random going 75 mph. I'd be at a stoplight waiting on a red light, and my car would rev up inching my car towards the line. Basically, my problems were unstable idling and shifting, where I found myself learning to coast in neutral on freeway downhills, or to use neutral at the light. Then I found this page amongst a sea of those recommending to replace the TPS. This was the best I'd found.

Though it was a pain in the ass to remove the 3 insanely tight T20 screws, this fix so far seems to be working. My car is purring again, idling at a solid 600 RPMs. I took it out on some extended errands this afternoon on the freeway opens through the city, and no a single issue. The check engine light is gone as well. Fingers crossed, this worked.

Thank you so much for posting this fix. I truly appreciate it. I registered for this website just to say thanks.

 

[bob4432]

Thanks for the info, very helpful

 

[bob4432]

Went to the local auto parts store this afternoon because of a check engine light on to get the code read. The guy read the code - P0123 like others in this thread, and said he was not going to erase or reset it which was fine with me as I plan to get it checked by a mechanic. While driving home from the auto parts store I was paying attention to the tach and engine noises and not the indicator light...

This evening I ran an errand and the light is off. FWIW I have never noticed any abnormalities with the engine revving or anything like what has been explained in this thread. Idle in 'PARK', the tach shows 6-700 rpm w/ or w/out the A/C on.

Now my question is did the guy reset the code accidentally while telling me he didn't or can this issue rectify itself w/out intervention? Also, if he did erase/reset the code, how long can it take to come back on?

Thanks in advance,
Bob

 

[megatone]

bob4423......

Resetting a code wont rectify an operating condition of the engine. If the engine has a fault with the CEL on, you can clear the code (CEL) but the fault will still be occuring. Once the ECU runs thru it's drive-cycle, it will light up the the CEL again. The DTC #P0123 is indicating an issue with the TPS....The TPS is affected by heat, humidity, carbon build-up, elctronic corrosion.... If you had the P0123 code and it went away, it just means that the ECU went thru another drive cycle and the trouble wasn't recognized again. Could be a sign that your TPS is on it's way out.....If you scan for codes again, you may or may not ger a DTC code, but you may get a "pending" code. If I were you, I would drive the vehicle as normal and if/when the CEL comes back on (after clearing it), scan the computer, if the P0123 code shows up again (at that time), I would clean the TPS unit, reset ECU, continue driving as normal and if the situation improves (ie: no more cel), I would plan on replacing the TPS......another thing, if your vehicle is idling erratically, I would disconnect, then reconnect.....one at a time....the TPS, the IAC, the MAP sensors.....to see which ones change's the characteristics of the idle.

 

[bob4432]

bob4423......

Resetting a code wont rectify an operating condition of the engine. If the engine has a fault with the CEL on, you can clear the code (CEL) but the fault will still be occuring. Once the ECU runs thru it's drive-cycle, it will light up the the CEL again. The DTC #P0123 is indicating an issue with the TPS....The TPS is affected by heat, humidity, carbon build-up, elctronic corrosion.... If you had the P0123 code and it went away, it just means that the ECU went thru another drive cycle and the trouble wasn't recognized again. Could be a sign that your TPS is on it's way out.....If you scan for codes again, you may or may not ger a DTC code, but you may get a "pending" code. If I were you, I would drive the vehicle as normal and if/when the CEL comes back on (after clearing it), scan the computer, if the P0123 code shows up again (at that time), I would clean the TPS unit, reset ECU, continue driving as normal and if the situation improves (ie: no more cel), I would plan on replacing the TPS......another thing, if your vehicle is idling erratically, I would disconnect, then reconnect.....one at a time....the TPS, the IAC, the MAP sensors.....to see which ones change's the characteristics of the idle.

Thanks for the information, any idea how long the drive-cycle is?

 

[megatone]

Here's a link regarding the drive cycle:

https://www.google.com/url?sa=t&rct...FWhsDVyldFzNiYy6A&sig2=vPJCXkRG4_qa7w2VirjbZQ


I personally have found it much less frustrating to get thru the drive cycle by just driving the vehicle normally around town for 30 or 40 minutes then head out on the hi-way for 10 minutes.