21P2090008 recalls OM656 and OM654.
Posted: Thu Nov 12, 2026
It has been mentioned in other threads, but my E400d 4Matic S213 standard waggon has been experiencing problems with the turbo boost. It has been determined that the problem is caused by coolant crystals in the vacuum lines and actuators of the turbo actuator.
Can you tell me where this coolant is made? Don't quote me on this, but it seems like there's a vacuum line going to the coolant pump that limits the circulation of coolant when it's not needed, much like a stat. The pump is leaking coolant into the vacuum system, which is a major issue.
From what I can tell, this can lead to a number of problems:
1. The problem I'm having is that when coolant crystals accumulate in the turbo vacuum lines, it causes a loss of boost and puts the engine into limp mode. This is exciting when you're trying to overtake but your torque drops from 700 Nm to 70 Nm.
Brake boosters seem to be susceptible to the same problem, which results in the loss of servo assist.
3. In the worst-case scenario, the coolant could even spark a fire by shorting out the wiring of a vacuum circuit switch.
Fixing the pump leak isn't what this shoddy Mercedes fix is all about. I take it that they're not actually removing vacuum from the pump; rather, they're just updating the software and switching the switch to make the pump run continuously. However, the issue of coolant and crystals in the hoover plumbing remains unresolved despite all of that.
In addition, the recall does not apply to my vehicle, even though it is in the same year as 656 of the affected engines (2019). So far, MB has avoided answering my question about why not. I have also checked with the DVSA.
Have any of you had the recall serviced? Tell me which car it is, what year it is, and what kind of engine it has.
Can you tell me where this coolant is made? Don't quote me on this, but it seems like there's a vacuum line going to the coolant pump that limits the circulation of coolant when it's not needed, much like a stat. The pump is leaking coolant into the vacuum system, which is a major issue.
From what I can tell, this can lead to a number of problems:
1. The problem I'm having is that when coolant crystals accumulate in the turbo vacuum lines, it causes a loss of boost and puts the engine into limp mode. This is exciting when you're trying to overtake but your torque drops from 700 Nm to 70 Nm.
Brake boosters seem to be susceptible to the same problem, which results in the loss of servo assist.
3. In the worst-case scenario, the coolant could even spark a fire by shorting out the wiring of a vacuum circuit switch.
Fixing the pump leak isn't what this shoddy Mercedes fix is all about. I take it that they're not actually removing vacuum from the pump; rather, they're just updating the software and switching the switch to make the pump run continuously. However, the issue of coolant and crystals in the hoover plumbing remains unresolved despite all of that.
In addition, the recall does not apply to my vehicle, even though it is in the same year as 656 of the affected engines (2019). So far, MB has avoided answering my question about why not. I have also checked with the DVSA.
Have any of you had the recall serviced? Tell me which car it is, what year it is, and what kind of engine it has.