Hi: I get CEL once in a while and code is always p0410. After a few starts, it goes away but eventually comes back...lather rinse repeat. I put power to the main blower fan and it comes right on. How does ECU know to throw the fault code? I read elaborate thread about how it sometimes looks at the O2 levels and "concludes" the secondary air is not working. Do people just replace the solenoid valve (which test around 30 ohms I recall) or ?? This is 01 SLK320. Thank you.

 

On my 2001 230SLK, it was the emissions check valve, I used to get the code once and awhile then it became every few starts, I cleared and cleared the codes but it kept coming back.

Then I replace the check valve the code went away and never returned, my part was about 60 bucks.

 

Beeguz thank you for this info. When you say the check valve do you mean the thing screwed into exhaust manifold that receives the pumped air from the pump motor via the solenoid? Or do you mean the solenoid itself? V6 has a single solenoid then a Y splitter hose to a fixture screwed into each exhaust manifold. Does your car have the solenoid and a single fitting on the manifold I presume?

 

My car has a single check valve its located on the right side of the car looking down at the engine its on a 3/4" tube that runs over to the throttle body on a 4 cyl.

This is the closest view I can find of the valve I changed I also took off the other valve in the line going over to the throttle body and I cleaned it inside they get dirt and moisture in them then the vaccum can't operate the valve inside clean yours out if you have one on your 320

In this pic its showing the valve they changed my car is set up like this one in the pic the goldish color valve with the red line, shows the location on my car.

https://www.benzworld.org/attachment...-60-jpg.98151/

 

That cadmium color valve; is that something to do with EGR? Secondary air is a different system I think. But maybe they are interrelated... Thank you.

 

The 230 does not have an secondary air pump, it uses the super charger,I read that the 6 cyl cars have an electric pump.

I checked at the mercedes benze parts store it shows the air system for your car it doesn't have the same valve like my car.(hehttps://www.mbonlineparts.com/oem-parts/mercedes-benz-a-i-r-pump-0001403785?c=bD0xJm49U2VhcmNoIFJlc3VsdHMmYT1tZXJjZ WRlcy1iZW56Jm89c2xrMzIwJnk9MjAwNCZ0PWJhc2UmZT0zLTJ sLXY2LWdhcw%3D%3Dre is the page with the diagram and the parts in the system (

What you need to do find is the flow chart for checking out the 320's secondary air system, then go step by step until you can find the problem of the system that causes the light.

Otherwise you are going to be throwing parts at the car to get the light to go out, my car worked fine with the light on if your car works decent like mine did you really don't need to make the repair.

I sell the cars I drive if I had no intention of selling it I would have driven my car the way it was, but since I gave my electric car back to GM I made the 230 my daily driver until I can buy another Bolt.

Hope you find the problem.

 

Good to know how the cars differ 4c vs 6c. I had an electric mitsubishi which was fine as a city car but then the main battery began to fail and to avoid financial ruin I traded it at a mitsubishi dealer while it still had value and where this benz had been traded in on something. Talk about your apples and oranges! Hope you can return to EV as I know someday I will also but right now we are being experimented on and I don't like that. At least a ICE car is more a known quantity. Certainly I do not want to just buy parts experimentally and the car does drive fine, no issues with anything I can perceive. Eventually I would have to get it emissions tested and the presence of a light is a fail no matter what. I will keep hunting for a comprehensive diagram of the 6C car aux air setup. Thank you.

 

You can pull off that part of the dash off where the EGR bulb is, then remove the bulb, your light is being cause on the morning start they can't check that on an emission test

There is always a way to get around it.

 

I went through exact diagnostic procedure described on pelican parts site. The left side valve produces much less noise in the output pipe than the right side one. The fan motor works and the solenoid passes vacuum to both valves correctly. So now do I open up that valve and try to repair it or buy one for $140 and hope that fixes it?

 

Me, if I knew that the problem would be fixed for good, if I spent 140, and if I could afford to spend 140, I would buy a new part.

I would check around for the part number,when you get the part number, you can search just for the part number, instead of searching a general term like secondary air valve.

I buy some of my parts at Autohaus AZ they have OEM and aftermarket parts when they are available.

Here is the part I think you mean for 120, but you would know better when you see the piece.
https://www.autohausaz.com/pn/MB-0021403560

 

Beeguz thank you for this and the part number is indeed the right one. This price beats the others. The thing is I am not positive this will stop the code from appearing. I do not have the deep knowledge to be confident about it. Still wondering how the system decides to throw the code. Does it look at the 02 sensor data and conclude the secondary air system is not moving enough air? Because this unscientific analysis I came up with only might suggest the left side is not getting enough air flow and the sensor might know it. But only a guess. Paying for star system hookup to see what is wrong will cost at least as much as this part.

 

I read everything I could about the code that my car set, then I eliminated the items one by one, the check valve on my car was the last thing it could be.

The only thing you can do is eliminate each item that can causes the code, on my car it was only the valve that worked by vacuum, or the larger check valve.

I cleaned and checked the vacuum valve, I pulled a vacuum on the valve by sucking on the hose I could see the valve try to move that meant it was working, while I had it off I cleaned it because it was sorta dirty inside.

There has to be a way of checking that valve, take it off and clean it, maybe you will see something wrong along the way, like a stuck valve stopping it from working.

Good luck

 

Hi Beeguz: Yes my plan is to work up the nerve to pull off the one that made less noise when vacuum was put directly to it. And if it can be dismantled, all the better. On pelican it says that the code is lit up when the ECM detects wrong values from the O2 sensors. So if the valve were not allowing enough flow, then the readings would be out of expected range and there you are. It sounds like you did not take your valve apart though. My vacuum pump is failing and must buy a new one to continue this process. How is your car otherwise? Any other gremlins? Mine has the BAS/ESP light a constant annoyance. Thank you.

 

No the valves on my car can not be taken apart, the check valve is a pressed piece its pressed together and is not meant to be taken apart, there is no way to put it back together if I took it apart.

The other valve that is vacuum operated was just dirty I cleaned it and checked it worked then put it back on the car.

I bought my car almost 3 years ago, it had a few problems when I bought it but it ran great and it only had 75K on it, I paid $5K for it tax and all.

The most expensive repair was a new radiator it cost me a little over a 100 for it, I changed it because they car overheated with the air on since replacing the radiator I have no heating problems in 100 degree weather.

Right now all I do is keep my car clean and change the oil every 3500 miles, I changed all the fluids serviced the transmission right after I bought it, just dropped the fluid in it again I plan on keeping the transmission nice and clean inside.

Someday I will buy another one, if I can buy a low mile car, I just saw a low mile SLK for 8K on ebay today, it needs a door and a fender otherwise the car is nice if I just didn't spend money on building a jeep with a plow I would have bought it.

I love my SLK, when you get yours right you will love yours.

 

Beeguz if you live in NE PA, it is wise to build a jeep with a plow! We lived in SE PA for a few years and there were times I would have liked to have such a thing.
I do love my SLK even with this annoying trouble and the BAS ESP business. In a picture up above, you show a red arrow going to a thing that cannot be dismantled and I wonder if that is part of EGR which is separate from this secondary air business as far as I know. You have been a great help to me on this. Thank you.

 

The part in the picture is the valve I changed, however on my 2001, the check valve(the part I changed) is on the opposite side of the engine, that check valve has to close when the engine does a cold start, if it does not close the check engine light comes on.

I think the valve shown for your engine has 2 parts inside, the vacuum valve and the check valve, are in that one part, where my car had 2 separate parts your car has one piece deal with the both parts in it.

You should check around the net for the test procedure for the code set for your model for the code set.
The test procedure should walk you through the steps to check and evaluate the parts in the system.
Then you can zero in on the part that failed instead of wasting money buying things you don't need to get at this time.

For my car the procedure was to check the vacuum valve, make sure the valve moved when I applied suction, clean the valve and put it back on.
Then it said if the car put the check engine light on again the problem was in the check valve the part I changed.
When I changed the check valve my car stopped throwing the same code your car is throwing.

I must have cleared the codes 50 times with the same result, hoping it was a faulty code then within a day the check engine light would come back on.

I know its frustrating but you need to follow the procedure for your year and engine type to get anywhere with this code.

 

I would like to remove the left side vacuum-controlled valve that lets the fan air in to the exhaust port during the brief injection period. I want to clean it and inspect it. It is held on with a single male torx head looking thing. I don't even know what to ask for at the tool place so if anyone knows what to call this and what the number of it is, thank you. It looks like it might be ten millimeters across but hard to know how to measure it with all the points on it. With the full engine vacuum put to it, this one makes less noise in the pipe than the right one does when it gets full vacuum; thus my theory it is cause of the light. The fan motor spins fast and the electric vacuum solenoid is pulling and passing ample vacuum on command from ECU. Thank you.

 

I bought a set of those sockets from Amazon they are very good sockets and they are the black impact sockets which are stronger than the ordinary type.

For 12 bucks these are worth having if you own a Benz prouduct these bolts are all over the car so some day you will need them again.

 

If anyone is still paying attention, I can keep the light off if I keep the fuel tank higher than 1/8 and run with the check valve removed. This is $28 item from dealer but generic ones have wrong tube diameter for the hoses on the car. With pure vacuum going to the electric solenoid that sends the vacuum to the giant exhaust ports the electric motor blasts air into the stream during warmup, my light stays off.

 

What size tubing is the check valve you need?
I bought a few check valves that have 3/8" barbed ends, a 3/8 fuel hose is tough to push on it with clamps it would never come off.

What I have are check valves that go in line they are made of aluminum I think, or some type of light metal.

Mine are something like this got them on ebay.https://www.ebay.com/itm/40296275539...3ABFBM0rT126hf

 

Beeguz I never thought about a fuel check valve and amazed they are so cheap. I will measure the interior diameter and look into these. Thank you.