I have a 99 F150 4.6l. I got trouble code po122 - TPS circuit low input. The truck seems to be running fine. I have an aftermarket throttle body, throttle body spacer, and air intake. I replaced the TPS last year when it broke and Im pretty sure the its still good(according to some voltage tests I did). Where else should look to solve the problem? Thanks

 

Sorry to jack your thread but I also have a '99 4.6 and I think I'm having 4.6 issues, where is it located? Is it the sensor that's in front of the DPFE sensor? Thanks

 

its attached to the right of the throttle body, held in with two screws.
usually when they go bad, the rpms start going crazy, you have some shifting problems. my trucks a stick shift and when mine broke last time, i would rev up the engine and it would take a couple seconds to rev down. I replaced it and it hasnt been a problem till now. if you do try to replace it, be careful with those screws, there a real pain to get off,

 

I'd throw away that spacer.

 

If the TPS fails the test, replace it. Then figure out why they keep going bad. The original might have just gotten old, but if the current one isn't physically damaged, it's probably low-quality. Buy a different brand next time.

If the TPS passes, test its wires going back to the PCM, then test it again THROUGH those wires. If it still passes, the fault is inside the PCM.

 

The TPS is located on the end of the throttle shaft opposite the throttle cable. It has three wires attached by a plug. One wire is 5 volts for power, one is ground, and one is the signal voltage which is sent to the PCM. I believe yoiur code pertains to the signal voltage to the PCM.
This is adjustable by loosening the screws which fasten it to the throttle body, and rotating the tps slightly.


Here's a photo courtesy of some on in the L forum, your throttle body will be in a different location.

[IMG][/IMG]

 

what was the difference when you added the throttle body spacer? how do you think it would do on a stock 4.6??

 

Spacers are a total waste of money.

 

they make a cool noise!

 

i agree the spacer was a waste of money, didnt do anything as far as performance upgrade but makes a cool noise. when ever someone gets in my truck - they ask me if i have a turbo or super charger because of the whistling sound it makes. but back to my problem - maybe a bad connection somewhere? the truck seems to be running alright but im getting the PO122 trouble code - TPS circiut low input.

 

You may be able to adjust the voltage to correct the problem, or the device will need to be replaced. I would check the TPS before you start chasing wiring issues that may not exist.

 

Should I Stick With Buying The Tps From Ford Or A Cheaper One From The Part Store

 

You should TEST & adjust it before you even think about replacing it.