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?

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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?

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

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.

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

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.

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

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.