2001 SLK230 w/ P0243 & P0410 Codes - Still Cannot Fix! HELP!
 

I am working on a 2001 SLK230 with my father and we have been pulling our hair out trying to resolve a CEL. The codes are P0243 (Wastegate Solenoid A Malfunction) and a P0410 (Secondary Injection System).

So far, we have done the following to the car:

- Cleaned MAF

- Verified all clamps are tight and no cracks in piping

- Replaced Recirculating Air Flap ( AKA Air Bypass Valve)

- Replaced Secondary Injection Check Valve (PITA)

We cleared the codes, drove the car for about 60 miles and the CEL came back on throwing the exact same codes. We cannot get this car smogged unless we resolve this once and for all. Previous searches here have revealed that leaking cam sensors can cause all sorts of electrical problems. We have inspected the sensor and the wiring and found no traces of oil (thank God). Are there any other options I am missing? One big one is that we aren't sure if we did the air flap learning procedure correctly.

Have you replaced the K40 power supply relay?

There was a K40 relay on 2001 facelift cars???

Bump

I have replaced the relay (the K40 relay is called the Engine Management Relay now as of 2001, part no. 170 545 02 05). The CEL came on this morning. P0243 and P0410 codes. It's the same freaking codes. Very frustrating. I have new recirculating air flap, new check valve for secondary injection and now a new relay. Still, the CEL won't disappear!

Help. I am losing my patience with this car and fast.

Have you confirmed that the supercharger is actually working?

Supercharger is working. On 2001+ cars, there is no clutch that automatically activates or deactivates. The whine confirms it is functioning.

When the light comes on, there is no loss in power or limp home mode trigger.

not sure but dosent the computor use the 02 sensor to monitor airinjection, could it be the o2 sensor is faulty,not recognizing air being injected?

Wouldn't the code for an O2 sensor show? One thing that is on my mind is if a boost leak is throwing this code. We have confirmed that all vacuum lines are attached though.

P0410 codes can be caused by faulty o2 sensors and you can have no o2 sensor MIL codes present. Have you verified that vacuum solenoid Valve that supplies air to the check valve is working?

Maybe the p0243 code is telling you there is a problem with that valve?

I'd also check to make sure the valve had vacuum at the input port.

With the SDS shop tester in activations screen, i could turn on airinjection, and o2 is required to be less than 40 mv ,with my bad o2 sensor i only dropped to 60-80mv, unplugging a vac line such as purge line,02 sensor should immediatly drop to under 40 mv, replaced my o2 sensor and now mv drops to 17mv when activating airinjection, o2 sensor solved problem.

Nulu, are you saying that even with a faulty O2 sensor, a P0243 can still be set off in addition to a P0410?

I relearned the air flap two days ago and now the only code I am getting is P0243 with no P0410 showing. This may be because I have only driven the car 40 miles and the emissions monitors are still flashing, but the CEL is not going off even for the P0243 code that just popped up. My theory is that once the P0410 pops up, that may trigger the CEL again.

no ,only relating to po410

The age of the O2 sensor upstream is unknown (same with downstream). It's worth replacing it as the car has 129,000 miles on it. As for the P0243, we have confirmed there are no cracks in vacuum lines or the charge pipes (input and output intercooler pipes) and hoses to the MAF. I guess tomorrow I'll find out what the diagnostic says about the ECU and the emissions monitors. Again, this is not and SDS diagnostic from Mercedes.

There is an electrically operated solenoid that provides vacuum to the switch-over valve that actually directs the supercharger output into the check valve. It is located under a plastic cover at the front top of the valve cover. I'd bet the p0243 code is related to this solenoid not the waste gate.

I was told by another member in a forum that a P0410 and a P0243 is a sign the supercharger is failing on a car with over 120,000 miles. The two codes indicate that the boost pressure may be too low. The car is in the process of going through the diagnostics right now. I sure hope I don't have to replace the supercharger. :(

You've been misinformed.

Do a search on 'P0410 + C230' and review the 2 threads that come up in the search results.

Will do. I will see if those threads show a way to test the switchover valve (or shut off valve).

I take it replacing this shutoff valve may address both codes since I"ve already done the recirculating air flap (bypass valve) and secondary injection check valve at the back of the engine?

Tim,

Is this the shut-off valve? I have already replaced the check valve indicated in the picture. This is off someone else's site trying to address a P0410 but just replacing the check valve.

http://home.comcast.net/~hoeren/Disc...-140-68-60.jpg

UPDATE -

The car passed the diagnostics tests and pre-inspection for California smog. The shop cannot smog the car however since they are not CA certified. However, only one emission monitor is going off, no CEL. The emission monitor is supposedly related to the cats but is not an issue for smogging the car. The car is at the smog shop right now. If it passes, it is because relearning the air flap resolved the issue. More updates to follow soon.

Car has passed smog! Looks like relearning the air flap fixed it. There is still that one emissions monitor that bugs the hell out of me. It might still be related to the shut-off valve and/or an O2 sensor that is old. I guess it wouldn't hurt to change both later on.

Nevermind! The effing CEL came on again! Same codes!! Help. This is getting ridiculous.

I found the change-over valve; it's the solenoid you were talking about! It's only $37 so I am buying it.

Part Number is 002 540 14 97 EGR Changeover Valve (or Solenoid)

That is the solenoid I was talking about, its triggered by 12V from the ECM and when activated it passes vacuum to the valve that actually admits the air from the supercharger via the check valve that you already replaced.

You can check the operation of the solenoid by activating the secondary air injection and monitoring the vacuum on the output side of the solenoid - you should see vacuum when the air injection system is operating.

I don't have the car in front of me right now, but when it fails, does the solenoid open, directing air into the secondary injection, or does it fail closed?

kind of depends on how exactly the valve failed (if it has failed, I wouldn't replace it without a diagnosis) I'm guessing the more likely scenario failure would be air-injection off mode since the ECM only calls for secondary air injection mode maybe 2-3% of the run time to manage O2 temperature.

We bought the part for only $25. At that price, we might as well replace it and see what happens. I'll update this thread if it's either solved, or if the CEL comes back on. Thanks for your help so far! Keep your fingers crossed!

It's back on! Whiskey Tango Foxtrot!

P0243 and P0410 again!!!

bump. I don't know what else to look for on this thing.

bump again.


If anyone has any other suggestions where to look, please let me know. I really want to be done with this, or get rid of the damn car.

It's been some time since I have updated this. I am still having issues. We replaced a damaged pipe running from the intercooler to the MAF in hopes that it would cure the issue. It did not. I also tightened and ensured all hoses and clamps were secured. Since the car was involved in a front end collision, I am concerned this source may be the intercooler since the ends are plastic mated to the metal core.

Any other suggestions?

Stop ****** around and change the ****** MAF and make it original.
This isn't rocket science cleaning it is completely useless.

For me the P0410 was caused by a corroded air pump check valve.
My original valve part # is 0021402860. That was replaced by a newer 0021406860.
I found an older check valve 0001407860 for $20. Tried it out for several weeks and the P0410 is gone for now. Let's see how it goes. If the older valve 0021406860 doesn't work, I will go for the newer 0021406860.
To remove the valve, you will need a 27mm or 1-1/16" low profile wrench.

I'm bumping my thread yet again with the same symptoms. It has a new MAF now and is still throwing the P0243 and P0410 codes.

K40 Relay? Rev it to 2500 RPMS. Does the supercharger kick in? If it doesn't, it's the k40 relay.

The car is a 2001. It does not have a supercharger clutch. The relay was replaced already in addition to the recirculating air flap and check valve at the back of the motor for the secondary air injection. We cannot get these codes to shut off for the life of us.

Stig,

I had a P0410 on my S320, and the emission components are similar in other models. I had a leak in the control vacuum for the air injection control valve, and the leak came from this little rubber female wye vacuum fitting that tapped into manifold vacuum near the throttle body.

In looking at post 18 picture the air injection is still controlled by vacuum. Follow the vacuum control line, and somewhere down the line is solenoid that controls the vacuum to air injection valve, and beyond the solenoid vacuum line check the line to the vacuum source. Very near the source is rubber wye that just gums-up and turns into in marshmallow. Check the line. See what the outcome is.

On my S320 the EGR was the same, but I believe on 2000's and above the EGR's are electronic

Check that out, and see where that takes you.

Best of luck,

Martin

Yes, it does have a supercharger. It's a Kompressor. Sounds like it's time to take it to the pros and have it hooked up to Star Diagnostics. It's called the Engine Mount relay aka K40 Relay. 2001+.