Harebear

Hey guys, just picked up a W215 CL65 AMG with low miles and its pretty down on power. I went ahead and pulled codes for it and what I got was

P2033 (Comparrison of the pressures between B28/6 (pressure sensor upstream of throttle valve), B28/7 (pressure sensor downstream of throttle valve), and Ambient pressure sensor in the control module N3/10 (Motor electronics control module). The ambient pressure is measured by a pressure sensor in the control module N3/10

Additionally I got a code for



So I went and pulled the pressure values with my scanner and what I'm getting is

Sensor:
B28/6 (Pressure Sensor Upstream of Throttle Valve) 2080 mbar
B28/7 (Pressure Sensor Downstream of Throttle Valve) 336 mbar
B28/4 (Pressure Sensor Downstream of Air Cleaner Left) 1003 mbar
B28/5 (Pressure Sensor Downstream of Air Cleaner Right) 1003 mbar
N3/10 (Ambient Pressure Sensor located on Motor Electronics Computer) 1000mbar

I already swapped B28/6 pressure sensor because I initially found an aftermarket sensor there with a broken stem. Was still getting codes, so I took it to the dealership

They're saying I need a new control unit but I I thought I'd double check with the forums bc that seems a little heavy handed.

mbwillgrubs

Why do you think these numbers are indicating a problem? Is the throttle valve downstream of the turbos?

Harebear

Well 2000 mbar is almost 30 psi, I can't imagine why there would be that much pressure but to be honest I have little experience with FI systems. That plus the code stating there was too much pressure differential between sensors.

Side note, I was getting incredibly high IAT temps so I went ahead and replaced the IC pump with a Bosch 010 I had lying around, since it still had the 003 on it. It did not help my IAT temps at all, even after a long bleed using the shrader valves routed to the filler neck. IAT temps getting up to 80-90 degrees over ambient. The pump is clearly flowing because I was getting flow from the bleed. So the only other thing I could imagine is the IAT temp sensor, but it reads accurately at cold startup, it just shoots way up once you hit boost and never comes back down

mbwillgrubs

I agree on the high pressure. I think mine is supposed to create 1.3 bar at max boost. So, that still leaves us with the crux of the problem. The other thing I would think would be waste gates not releasing the pressure. That is probably the problem, the question would be why. Is it something as simple as a line (vacuum or electrical) disconnected? Or, is the command signal not being created or received.
Also, are the numbers you stated at idle? I am thinking about the throttle plate being closed hence the high (maybe too high) pressure on the upstream side and low pressure on the downstream. This would make sense if the plate were closed. Have you tried this at part throttle just to see if the pressures balance? Is the throttle not responding correctly causing the backup of pressure.
Just food for thought, again, hope it helps.

Harebear

Solved.

It was the sensor all from the start. Mercedes parts gave me the wrong boost sensor from the start. I can't believe they were going to have me spend thousands on an ECU when even the ****tiest of techs(myself) was able to figure out it was a sensor.

mbwillgrubs

Glad you resolved your problem. How did you determine it was a sensor? Code reader or the like?

Harebear

Yeah pretty much, it was the same code I posted initially, MB apparently took that code to mean that the ECU was bad. Which is crazy, they were just trying to bilk me, I put too much trust in them but they tout how they're the biggest dealer in the country with the best techs 🙄

To be fair the "small" dealer I took it to later on down the road to bleed the coolant with their official MB vacuflush was superb and I'm actually moving both my cars there to be serviced from now on.

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