Hey guys, last year I purchased a used 2004 Lancer Ralliart (standard) which I have been extremely happy with, and have had no problems with, until now. Last night I turned on the car and immediately the check engine light came on. I proceeded to drive home and noticed I had almost no throttle (which I now know is limp mode) and I had to put the pedal down to the ground just to switch into 2nd gear.

Anyways, I took it into the mechanic today and he said the car came up with a P2121 error code which says there is a problem with the throttle position sensor (TPS). He called Mitsubishi parts and quoted me for $1500 to replace the entire throttle body as apparently they cannot just replace the sensor!

As of now I have absolutely no idea what to do, and I have been reading that the TPS may actually not be my problem. I hope there is someone out there that can give me advice or who may know what the real problem is so I'm not dropping $1500 on something that is completely fine.

Any help would be greatly appreciated!

 

Not totally sure what your issue is, but that is a huge rip off on the Throttle body price. You can go to car-part.com and get a throttle body for less than $50 and install it yourself in less than 20 minutes. You can try cleaning your Throttle body and see if that helps.

 

Try cleaning first is right, use Deep Creep by Seafoam, if that doesn't work, then look for a used one. I went with the Galant TB, it's a bit bigger @ 63mm and it cost about $66 shipped.

2004–present Mitsubishi Endeavor
2004–2009 Mitsubishi Galant
2006–present Mitsubishi Eclipse
2005–2008 Mitsubishi 380

You could also check the classifieds here if you want to find a stock size one.

 

on the 04 there might be a recall have to call your local dealer and ask the parts person if there is and does it apply to your model

 

You didn't happen to have just changed a headlight bulb right before this happened, did you? Many times, people will unplug the accelerator position sensor (directly aft of the right headlight) in order to gain a little more clearance when changing bulbs, and forget to plug it back in afterward.

Also, if your mechanic quoted you $1500 for a new throttle body when this has nothing at all to do with the throttle body, you should find a new mechanic.

From the service manual:

 

Yeah, isn't what the manual refers to as the "Accelerator pedal position sensor" most of us call the throttle position sensor? Isn't it just a relatively inexpensive potentiometer?

What is it on the throttle body that the mechanic might be referring to, a servo motor that actuates the throttle plate?

 

Awesome thanks for the advice guys, I'm going to talk to Mitsubishi tomorrow instead of my original mechanic just to see what they think, but I have a feeling it was just a loose or dirty connector as I haven't had any other problems all weekend.

As for the headlight I have not done any modifications to it or the rest of the car other than a catback exhaust, but that was done last year.

 

I've noticed that most people are reluctant to take their car to the mechanics at the dealership. You gotta realize that sometimes you have to. These are experienced guys who have factory training and work on a particular make all the time. The electronics of course, but even mechanical part analysis and replacement is more and more requiring specialized knowledge and tools. Ask to talk to one of them, and get past the "manager" at the desk - it takes away the fear of getting hosed.

 

I have a 2004 Lancer Ralliart that I bought brand new and still love just like it was new.

I have had the same problem on and off for about 2 years. It shows the same symptoms with the CEL and I check the scanner and get 3 codes. I can't remember what they are right now, but the refer to the TPS. One of them said loose or disconnected wiring to the TPS.

I have found that the accelerator cable is attached to a spring looking thing right by the back of the passenger headlight. If I unplug that and blow any dust out and then plug it back in, I don't have the problem for another 6 months. Last time I had the problem, I sprayed WD-40 on the spring looking thing, not inside any electronic components, just on the outside of the unit and also where the cable connects.

So in my opinion, it does not sound like the TPS is the problem. I don't know if that thing connected to the accelerator cable is the same as the TPS because I understand the TPS to be on the throttle body. Perhaps that is the Accelerator Position Sensor as was mentioned above.

I know you posted this 4 months ago, but next time you have that problem, try what I did and see if it works.

I can post a photo if needed, but it should be easy to find that thing by the headlight. Sorry, I am not a mechanic, nor do I have a repair manual so I don't know what it is called.

 

It's the accelerator pedal position sensor. guy above me for safety sake you may want to look into purchasing a replacement. You don't want to be stuck in the middle of know where in limp mode.

 

lol, limp mode sucks

 

There has been so much talk about the accelerator pedal sensor here lately, and now mine is on the fritz. code P2135 is coming up on my car a couple times a week.
The ebay code reader has saved my butt a few times already.

 

Thanks for more info on the issue. When I went back to Mitsubishi they suggested I wait until it does it again before I drop the money on a new sensor. And luckily since march it has not gone into limp mode since so I think it may have just been a fluke?? But I will keep an eye on it.

 

Yup I just cured this problem on my 04 RA last weekend. Sensor kept throwing me in limp mode, code reader wouldnt reset it. Stuck me with no accelerator for more than a week. Got on Mitsubishiparts.net and they had a new sensor to me that weekend! So glad to have solved this problem! Its a pain in the butt!

 

I am having the same problem, how hard is it to swap the part out? And does anyone have a part number? Thanks in advance.