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P1542 - Pedal Position Sensor - kick down switch ?

25K views 9 replies 5 participants last post by  Lilppbilly  
#1 ·
Anyone care to speculate as to why I get a "P1542" code, complete with limp mode, and have to pull over and reset ...ONLY when I stomp on the accellerator pedal? Seems like the kick-down switch is causing the fail.
I had the throttle body and CVV replaced about 10,000 miles back. Car now has 145,000 miles, running perfectly otherwise.
Y2K 528i Sedan, steptronic transmission (GM). :eeps:

Thought I might replace the kick-down switch since it's cheap. Or "block" it...?
 
#4 ·
Update on this issue; I purchased a Creator C310 v.5.1 scan tool in the hopes of getting more info. This is what I have:

75 Plausibility, signal, pedal travel sensor (in thr.) pot. 1/2 (OBDII : p1542

I know this indicates I need to replace the entire throttle housing; but I am not anxious to do that since a good Indy (Moran Motosport) just replaced that a year and a half back (6,000 miles back)...and it ran just fine until last month.

It ONLY goes into limp-mode EML light when I stomp on it (and thereby) initiate the kick-down...NEVER occurs when driving gently or "normally".

Interestingly, It does NOT happen if I fish my toe under the pedal and kick-down just by using the switch under the accelerator pedal...so I guess the issue is either in the TB, or possibly in the bowden cable someplace?

Mine is the Y2K 528i M52, with cable connection from pedal to throttle body. GM auto transmission.

Throttle housing 13541433414. Housing is about $600 plus labor...not sure how difficult this as a DIY?

Helpful suggestions welcomed...
 
#5 · (Edited)
The throttle body is not hard to replace. You have to remove the intake to the TB, remove the idle control valve and unbolt the throttle body.

I would clean the TB first. Remove the intake to the TB and very carefully open the throttle plate and clean carbon from all surfaces as best you can. Do not open the throttle plate and let it slam back into the idle position. That'll ruin the TB for sure. I'd use come type of lube spray to clean up the carbon (and that in the idle control valve. The moving parts need some lube to operate properly and a product like brake clean will remove all the lube.

If you feel it necessary to remove the TB to clean it, make sure you buy a new TB gasket. It is a profile gasket and will certainly be flattened out and not work if you try and reuse it. And make sure you spray the electrical connector with a very good electric cleaner and that you twist it on securely. I always recommend Deoxit-it dissolves corrosion and leaves a coating that prevents further corrosion.
 
#8 ·
Follow-up / close-out.
It was indeed the throttle position sensor, which, on my car, is incorporated within the throttle body and not serviceable on it's own. So I brought it back to my Indy, who very graciously replaced it on the 2-year part warranty. They said these TBs just crap out from time to time; even when less than 2 years old...I certainly hope this one lasts 15 years like the OEM did...or if not; then dies in less than 2 so I can get it replaced again on the BMW OEM parts warranty.

All is good again; just need to clean the AM antennae contacts so I can get the Giants on the radio.