pojr

Does anyone know where the throttle position sensor is located and how easy it is to change. My 2001 SLK320 lost power and the code says PO120 for the bad sensor. I have not been able to find out where it is located to change it.
It is a manual transmission if that matters.

Any help would be appreciated.

Buellwinkle

Welcome to the forum. Maybe you are referring to the pedal travel sensor. Check my website, SLK stuff under Resources, component locator and search for pedal, it has a picture of where it's at. Also, it's $105 at Duval Motors if that helps. Of course manual transmissions matter, it's the best way to go, hate slush boxes.

pojr

Hey, You are correct that manual is the way to go. I have never owned an automatic car, and I have owned 10 cars so far.

Your site is great. That helps. Not sure if it is the same thing but it gives me something to go on. When I look up parts they never show the throttle position sensor for the SLK but do show it for all other MBs with the 320. Very odd.

Buellwinkle

Cars with throttle by wire have pedal position sensors instead.

DickB

Careful. You car has both an accelerator pedal position sensor and a throttle position sensor. They are two different things.

pojr

So what is the difference and what do you know about it. I can't even find the parts on the web.

DickB

The accelerator pedal sensor is located at the pedal in later model cars and under the hood at the end of a cable on earlier cars. It tells the ECU how hard the pedal is pressed. The throttle position sensor is located on the throttle body near the intake manifold. It tells the ECU where the throttle is set, part of a feedback loop. I have a 230, so I can't give you an exact location. It will probably have 4 wires connected to it.

pojr

Thanks. That helps!! I have been unable to find any real information on the web. I tried to buy shop CD, but none work on a mac Now I can take my VIN to the dealer and at least understand what I need to ask for. I could not even find the parts on the web.

DickB

I've been using alldatadiy.com for my SLK. The initial cost is a bit high - I think $25 for a year - but after that I was offered steep discounts for extended subscriptions, so if you plan to keep the car a while the cost is more reasonable. I found the information quite good (it's from Mercedes) although at times a bit hard to navigate. It has definitely proved worth the cost to me.

robert_in_la

I have the same problem right now. Just got back from AutoZone - pulled the code and it is also P0120. Have not idea what to do.

DickB

The throttle actuator has two potentiometers to provide feedback to the ECU. If the ECU picks up a faulty signal from one of the potentiometers, it will switch to use the other, but will limit throttle to 60% and set code P0120. The fault may be in the wiring or in the potentiometer or throttle actuator. If it were my car, I'd try a voltmeter at the actuator to verify a faulty potentiometer rather than faulty wiring or connector before replacing the part. If this is an intermittent rather than a solid failure, it could be difficult to diagnose. If it is the potentiometer at fault, I suspect that the entire throttle actuator has to be replaced as a unit. If you can't find parts on line, you may need to check with your dealer's parts department.

robert_in_la

Thanks for the info. What kind of money are we looking at if the throttle actuator needs to be replaced?

pojr

I could not find any parts online so I went to the dealer. They needed the VIN to determine the correct parts. On later cars the entire pedal assemble needs to be replaced. A reputable shop said it could go as high as 1200, depending upon what is wrong. This shop is top rated on checkbook, so they are trustworthy. It depends upon the model too, as the second sensor is not easily gotten too on some.

robert_in_la

Well it turns out I need to replace the gas pedal... $149 for the part.

Thanks for all the info.
Robert

pojr

Looks like mine was the same problem with a bad pedal assembly. Really the electronics went bad, but they have to replace the assembly. I hope that takes care of it. If it does not I will repost.

navreet

What is the part# for the Throttle Paddle/Sensor for the 2001 SLK320? And, where did you get it for $149? Thanks.