An illustrated guide to replacing your APPS - Part 1 (1 Viewer)

[Chaser717]

I got the cel and vsc off lights and all that jazz yesterday. No limp mode yet. Got a P1126 code from my reader. Reset it, on the third crank, same thing with the cel and vsc off lights. I’m thinking of trying to replace the TPS first as it’s the least expensive option to start with.
This is what my reader gave me... any thoughts?

 

[Cod55155]

what’s does this APPS LOOK like. is it at the end of theft tb or on pedal ?

 

[trudd]

I got the cel and vsc off lights and all that jazz yesterday. No limp mode yet. Got a P1126 code from my reader. Reset it, on the third crank, same thing with the cel and vsc off lights. I’m thinking of trying to replace the TPS first as it’s the least expensive option to start with.
This is what my reader gave me... any thoughts?

Hey @Chaser717. So I chased the 1126 for a long time. I would show up each March once things started to warm back up in Texas. Performance was never an issue, but it made me pucker up when getting the car inspected. So I replaced both the APPS and TPS and it still came back occasionally over the course of a few years. After developing a dead spot on the new APPS sensor that caused me to lose power at 75mph (and have to pull over on I-40 in NM to rest and restart the car), I bought an entire take-off throttle body complete with sensors and haven't had a single issue since.

The cost of the used throttle body and sensors was less than the new APPS+TPS sensors I installed on the old throttle body. Wish I had just done that the first time around.

 

[Chaser717]

Hey @Chaser717. So I chased the 1126 for a long time. I would show up each March once things started to warm back up in Texas. Performance was never an issue, but it made me pucker up when getting the car inspected. So I replaced both the APPS and TPS and it still came back occasionally over the course of a few years. After developing a dead spot on the new APPS sensor that caused me to lose power at 75mph (and have to pull over on I-40 in NM to rest and restart the car), I bought an entire take-off throttle body complete with sensors and haven't had a single issue since.

The cost of the used throttle body and sensors was less than the new APPS+TPS sensors I installed on the old throttle body. Wish I had just done that the first time around.

I took it to a shop and they dug around and cleared the code, said I needed a new TPS. I found a new throttle body for $437 with new sensors and all. But since they cleared it, the light hasn’t come back on so I don’t know. I may just put in the new throttle body in anyway just to renew the whole thing. But still hang on to the old one just in case.

 

[trudd]

Yeah my light would stay out for months at a time and then come back right before it was time for the annual state inspection. HAH. YMMV!

 

[bobNoobie]

huge YMMV,
I spent all my money trying a new TPS, then a new APPS, then a junk yard ECU (LOL) some mechanic thinks its ECU issue. ,then a junk yard TB.. wasted almost $1000 trying various things. problems just never goes away. it makes it more persistent ...

Being an idiot of me, I could not return any of the parts purchased above.

then the final fix was a brand new OEM TB (with all the sensor) for $1200 from the dealer.

ouch is ouch. but I learn my lesson.

 

[jhollander]

I just replaced my TB this past weekend. Picked up the new TB and gasket from McGeorge and installed following the FSM. It wasn't difficult at all. Hardest part was getting hoses to release after 20 years.

I would highly recommend going this route vs. chasing down each sensor. There's one sensor you can't buy unless you buy the TB and from talking to a few shops it's usually the one to go.

YMMV of course

 

[Rolocado]

I got the cel and vsc off lights and all that jazz yesterday. No limp mode yet. Got a P1126 code from my reader. Reset it, on the third crank, same thing with the cel and vsc off lights. I’m thinking of trying to replace the TPS first as it’s the least expensive option to start with.
This is what my reader gave me... any thoughts?
View attachment 2606671

Going through this right now... I have a used throttle body I can swap the TPS over to, but if the code comes back, I'm just going new throttle body route for $460 or so. Not worth the worry in my mind.

 

[bryce470]

I just changed out my APPS in a 99 LX 470. A few notes.

HUGE NOTE: I had to unplug the battery for 20 minutes to reset the computer for the new sensor to work.

Installing the new sensor is extremely easy if you follow the advice given in the OP and insert 20 degrees or so (10:30/11 o'clock) counter clockwise then rotate the base clockwise to position. You are letting the catch that is sticking out of the sensor rest against the top bolt sticking through the housing.

I was trown off when installing the part. I assumed the intake valve would move with the APPS. It doesn't, it only moves at the very end of the throw. I think this explains how the lemp mode works too. If the sensor isn't working correctly the valve can still mechanically open a little if you push the throttle most of the way down.

I spent hours going back and forth with the original part and the new part when the new part wouldn't work. I thought maybe it was because the original part ended in 10 and this one ended in 11. I thought I may have somehow installed it incorrectly. It didn't work because the ECU needed to be reset.

 

[bouncylexus]

Could be APPS TPS or the Throttle Body Motor/Clutch or the gear train inside the throttle body. I think I'm a little outspoken about this but have posted several times that I'm pretty sure it's a mechanical bind inside the throttle body that leads to a CEL pointing to one of the 3 electrical parts on the Throttle body.
I replaced the entire throttle body with a new OEM which includes the TB, Motor, TPS, APPS so no more guessing for me and have been great for more than a year with zero re-occurances. (had become a weekly affair)

How difficult was replacing the throttle body? Any gotchas?

 

[AimCOtaco]

How difficult was replacing the throttle body? Any gotchas?

It's pretty easy, without any real potential for problems. You might loose a splash of coolant and you should have a new gasket ready when you remove it (its more of a framed 0-ring than a gasket so not really reusable).

 

[skiller1234]

Question on TPS VS APPS. So my symptoms seem to match this thread better than any other. A couple times last winter my 99 LX470 stalled when coming down from the mountains in the winter. Tried a few things, the last was to replace the fuel filter as it was cheap and a possible culprit. Seemed to work as it has driven fine until about a week ago - when I had stalling issues again - but only in very cold weather at night (single digits). When it dies, either the RPMs just drop all the way out when stopping, or when I give it gas, the throttle goes kinda haywire, bouncing around first - then a stall. Sometimes it starts right back up again, sometimes not. In warm weather (above like 20 or so) it drives fine. The only codes I pulled were for misfires on all the cylinders - I reckon from stalling. Does this seem to fit either the TPS or APPS better? Can anyone think of any other possibilities? Tell you what - pretty scary when that happens driving down a curvy mtn road!!

 

[lcruzrlvr]

Just followed these instructions for my 2000 100. Not a difficult job - just patience and gentleness. Had one rubber hose disintegrate and the harness connector tab broke off. Both are temporarily fixed until I get those parts in.