Re: 08 CLK350 M272 P2004/0521
Posted: Mon Mar 16, 2026 6:59 am
Still learning how to use DAS (currently in simulation mode because the car is elsewhere).
Here is the code setting criteria, FINALLY.
I didn't realize you could just click on see more info and then F2. It opens an HTM file in the browser. Then just print as PDF. I found it by searching the path before I realized you can get to it directly from DAS (duh). Interestingly it states the MIL is not illuminated. So that part tracks. Here is the exact 0521 code setting logic:
Or I'm being dense and it just means "if the voltage state of the hall effect sensors don't change from 5V to 0V in less than 5 seconds, that is an error condition and it needs to happen 'many' times before setting the code.". German translations can be an impediment.
Prereqs:
Here is the code setting criteria, FINALLY.
I didn't realize you could just click on see more info and then F2. It opens an HTM file in the browser. Then just print as PDF. I found it by searching the path before I realized you can get to it directly from DAS (duh). Interestingly it states the MIL is not illuminated. So that part tracks. Here is the exact 0521 code setting logic:
The checking duration is "less than 5 seconds." It would make more sense if the error state needed to exist for 5 seconds but I don't know what less than 5 seconds means.- Fault if the signals from both position sensor do not change from about 5V to about 0 V. The fault must occur many times. Possible causes: tumble flaps are not actuated for an actuation, vacuum supply or aneroid capsule defective, tumble flaps are swung back into the test position after the last actuation, short circuit to ground on both position sensors for the tumble flap, linkage.
Or I'm being dense and it just means "if the voltage state of the hall effect sensors don't change from 5V to 0V in less than 5 seconds, that is an error condition and it needs to happen 'many' times before setting the code.". German translations can be an impediment.
Prereqs:
And an interesting known bug:- Battery voltage 11 to 16 volts
- Blocking time after starting, approx. 26 sec. expired
- No electrical fault on intake manifold tumble flap switchover valve
- Engine load less than approx. 30%
- Coolant temperature greater than 60°C
On an extremely hot engine compartment it is possible that a fault is entered. Delete fault if the Tumble flap switchover is OK (linkage, vacuum supply, aneroid capsule and tumble flap do not jam).
Exactly observe installation of a tumble flap position sensor at the prescribed torque of 6 Nm!
The tumble flaps are moved via an aneroid capsule and a rod to the flap shafts.
The intake manifold tumble flap switchover valve is integrated in the vacuum line to the aneroid capsule. If it is deenergized, the aneroid capsule is ventilated and the tumble flaps are lowered in the intake manifold (closed position).
If the intake manifold tumble flap switchover valve is actuated by a ground signal from the ME control unit, vacuum passes from the intake manifold into the aneroid capsule. The tumble flaps are actuated and turn in the intake manifold. This closes the intake manifold by around 50 %.
To diagnose the tumble flap switchover, the position sensors detect the mechanical limit positions of the shafts. The swivel range of the tumble flaps between completely swiveled in or out is approx. 56°.
There are two cylinder magnets with different polarities attached on every tumble flap shaft. Once the tumble flaps have swiveled out a cylinder
magnet as on the Hall sensor and the position sensor transmits. The signal at the ME control unit is about 0 V (tumble flaps actuated).
Swivel the tumble flaps back again and the other poled cylinder magnet on the Hall sensor is in the rest position. The position sensor opens and interrupts the connection to the ground. The signal at the ME control unit is now about 5 V (tumble flaps not actuated).
The position sensors must switch no later than approx. 5° before the respective limit position. For reasons of tolerance, they may also switch up to approx. 16° before the limit position.