CEL P0243 Malfunction in Wastegate Solenoid A Help Please!!! - PeachParts Mercedes-Benz Forum

#1 02-19-2006, 02:25 PM

CEL P0243 Malfunction in Wastegate Solenoid A Help Please!!!

In cold weather, below 10-15 degrees, usually has a check engine light. The code is consistently a P0243. As the day warms up and I go through the driving cycle, the light will reset itself.

What should I do? In warmer weather, 15+ degress, it is fine. When the CEL is on, I notice a reduction in power - like I am not getting any turbo boost.

I want to fix this problem but am at a loss as to where to being or what to do.....

Can anyone help?

#2 02-20-2006, 02:03 PM

I have cleared the codes and it was fine because it was above 15/20 outside. I know it will happen again, it's quite a pattern.

I have tinkered, but I am at a loss as to what it could be? Is this code very specific or could it be a lot of things?

Thanks!
Richard

nhdoc · #3 02-20-2006, 07:09 PM

I reported on having this exact problem with my '98 on a particularly cold morning. It happened once, just as you described it and hasn't happened again since that time a couple of months ago. My own gut feel is that it is a problem which will eventually get worse and occur in warmer and warmer conditions but hasn't as yet ever happened to me again to me so maybe I'm wrong about that.

I really wouldn't pursue it unless it became a regular thing as it is probably just something "gunked up" which clears itself up once a little engine heat hits it. When it fails totally it will be easier to find. It doesn't seem to be terribly serious...even if the wastegate was stuck open for a brief period it would seem not to do too much damage as all that does is dump the boost rather than allowing it to feed into the intake. It basically reduces our turbos to the performance of the normally aspirated OM606 until it clears up.

#4 02-20-2006, 11:36 PM

I did some work today. I removed the vacuum line that goes from the wastegate to the wastegate actuator. When I did this and took it out on the highway, it always set a check engine P0243 when I hit about 65-70 mph. I would reset the code and try again. I was able to reproduce it 4 times. Then, at the side of the road, I reconnected the vacuum line. I ran the same stretch of road and didn't set any CEL.

Unfortunately, in Colorado, it sets a code almost every morning. I know have to do some research on the Wastegate Actuator.... Maybe that is sticking....

Any ideas?

nhdoc · #5 02-22-2006, 04:22 PM

I shot a photo of the wastegate actuator as shot from beneath the car and this part is attached to the "black box" which is probably what they call the wastegate solenoid which has a vacuum hose coming out the top (which goes to this actuator) and a vacuum hose coming out the bottom that presumably goes to a vacuum source. It seems that the "black box" or solenoid regulates the vacuum to the actuator. If I were you I would attach a mighty-vac to the actuator and test it to make sure it is not leaking, but I think it is probably good as the loss of power would indicate the solenoid is not relieving the vacuum (assuming that when vacuum is applied to the actuator it dumps boost). If the actuator is good then I would look to replace that "black box". At least price it out at the MB dealer and see if it is worth trying a replacement out to see if that cures the CEL.

#6 02-22-2006, 11:14 PM

Thanks. I'll let you know.

Richard

nhdoc · #7 02-28-2006, 09:34 AM

OK, today it was cold here again in the teens when I started out and I got the same CEL light accompanied by a no-boost condition which I am assuming is the P0243 fault again. Strangely I also noticed the heat was only coming out of the side top vents and not from the floor which is also supporting a vacuum problem, but I had vacuum in my brake booster so I think the problem is in the solenoid valve and not in the vacuum pump itself.

I discovered an interesting thing though. There is a second vacuum solenoid valve on the EGR circuit (look next to the ABS pump to find it. I switch solenoids and immediately the boost was restored. Also interesting is that there was this noise coming from the solenoid that I could never pinpoint before I swapped them. It is knd of a creeking sound after the car is shut down and continues for up to several minutes. Now that the "bad" solenoid is up top I was able to hear it clearly coming from it. So, I am convinced I have found a faulty part (maybe?).

My dealer does not stock the part (of course) it is #000 545 04 27, FYI and lists for $115. I ordered one and will replace the faulty one at the end of the week and report my findings. I thought you might find it interesting though to know you can switch valves and test with the EGR one in the mean time. Since yours is more faulty than mine you may throw an EGR code after the swap though.

raMBow · #8 02-28-2006, 09:44 AM

Information I hope I never have to use, but it is here and would have cost me $100 just to say hello to the dealer.

Nice, thanks and I have saved the link.

nhdoc · #9 03-02-2006, 03:36 PM

OK, I installed the new vacuum solenoid today and the car is still running fine. I'm sure I'll be able to test it out during cold weather in the next days as we are expecting another arctic snap over the weekend.

I decided to open up the old part to see if I could find the cause of the malfunction. This valve has 3 ports. They are labled "VAC" on the top center which is the vacuum source, "OUT" which goes to whatever actuator is being controlled and "ATM" at the bottom which goes to one of the external filter units that prevent dust from entering when it bleeds off vacuum.

OK, so the only issue I found when I cracked the old one open was some crud had accumulated on the seal under the "VAC" input port. That would be a problem as it could, in theory, create a vacuum leak or bleed off vacuum when the port is supposed to be sealed off from the atmospheric pressure.

Unfortunately I was unable to open the part up without destroying it, however, now that I see how it works it would be possible to clean it by spraying some lower pressure compressed air into the "VAC" port while leaving the other ports open to vent. You could then connect a mighty-vac to the VAC port and check its seal. This might just be enough to blow that crud loose off of the sealing surface and allow the valve to seal properly again.

It's worth a try anyway, rather than shelling out $115 for a new one without even trying anything. I'd even shoot a little rubbing alcohol through it to try and clean it up if the compressed air doesn't work. It's a rubber pad under the port which is supposed to mate to a plastic rim on the bottom of the VAC port tube. Any crud which collects there would prevent the pad from mating to the rim. In the photo I attached I show the two surfaces and how they are supposed to mate. The black stuff on the blue rubber pad is some of the crud in question. After I cleaned it off it was solid blue. That black stuff either made it past the venting filter or came from the vacuum source, but whatever it was it had accumulated right on the seat of that valve.

#10 04-19-2006, 06:02 PM

Potential Resolution: When I switched out the valves, between the wastegate and the EGR, the code did not change. It was still a P0243.

I never got an EGR code and the problem only happen immediately after starts on colder days (below 40). The problem then went away and didn't come back. I always reset the light immediately (just crazy). Anyway, if I didn't reset the light, but the end of my driving day it would have automatically turned off.

Upon using Mercedes Technical Website for $19 for 24 hours, I pulled down the manuals for the engine. I was able to get them in PDF format and they were a great bargain.

Anyway, the test procedure for the OBD-II P0243 indicated the proper voltage & vacuum. In one of the possible solutions, replacing the vacuum filter that vents to the atmosphere was listed.

I did that without any tests - it was quick, easy and cheap. When I did replace the filter vents and the problem went away. We have had about 6 cold mornings since then and so far nothing - it has been very consistent.

I didn't want to replace the actuator because the Wastegate code should have disappeared and an EGR code appear when I switched them.

Well, I'm not calling this one quite done yet, I just need some more cold mornings to prove it out - and I don't think I'll be seeing those for several months.

nhdoc · #11 04-19-2006, 06:19 PM

I thought about changing that little filter on mine but it looked pretty clean so I didn't pursue it. The thing with mine was, when it failed I also had vacuum problems with the heater doors so I suspect my solenoid was leaky and stuck open, venting all the vacuum to the atmosphire so my heater doors would not close. In my case the solenoid was the problem...I suspect it is yours too but like you say you will not know until next winter maybe...mine did it only on cold days too and after I changed it I never got another CEL.

I never got a CEL on the EGR system after I swapped them either...but mine was much less predictable than yours, it only threw a code a few times, on the coldest mornings.

F18 · #12 04-19-2006, 08:03 PM

Richard,
I am just curious.....what kind of digital message popped up on your dash board when the CEL came on. Did it indicate an "Electronic" Engine malfunction even though it was the small atmospheric filter attached to the wastegate solenoid?

#13 04-20-2006, 10:49 PM

The check engine electronics light warning displayed with the CEL light on. I also lost all turbo boost - it was like driving my old '96 E300 - real slow and revved high. Then after some driving it was fine.

Even though the filter looked clean, it did seem to have a little more resistance than the new one.

It seems that the atmospheric line attached to the filter caused the vacuum transducer to read outside of range. It would clear up though - and only happened on colder days after a cold start, always overnight. Then it would be fine.

When I swapped transducers, the problem didn't change and it should have.

So, I replaced the filter on both vacuum transducers and haven't had it yet. I won't call it done because I am superstitious and I need to prove it in more cold weather that we haven't had.....

BioE300 · #14 02-25-2008, 06:47 PM

The CEL light came on in my 99 E300 last week. The OBD-II code came back P0243. I live in Colorado and we have had cold weather (15 below) and very dry and dusty. It is warm today and the CEL Light is off and there appear to be no problems with the turbo or acceleration. Where is the Vacuum Filter you are referencing. I would prefer to replace a filter as opposed to a solenoid.
Thanks for your help!

TMAllison · #15 02-25-2008, 06:59 PM

There are a couple of them. One is inside the computer box on the right (pass) fender well; another on the opposite fender well. Am certain there are others scattered around too.