Car Owners Hub UK - Built by Drivers, for Drivers

Hello everyone,
A swirl flap problem has plagued my 2012 W204 c220cdi since I bought it a few months ago. The original P200A75 and P200A21 were the first to see this. I thought the inlet manifold was probably clogged after doing some research, but I was wrong.
So, I installed a new motor and replaced the manifold because it seemed like the most sensible solution.
In addition, I cleaned the intake tract and all of the necessary EGR components, and I changed the housings for the fuel filter, oil cooler, thermostat, water pump (with a coolant flush), and oil cooler.
We cleared the codes set during the job and restarted the car. We checked for leaks and oil feed, and everything is good.
As far as I can tell, the swirl flaps are still generating the fault code P200671, which indicates that they are blocked or jammed.
I reattached the old motor to the swirl flap, set it on the intake, and observed how it worked. The motor tries to swing to the closed position of the flap after the initial key ignition, but it stops after approximately 15 degrees and goes back to the fully open position.
Using my reliable multimeter and a few back probes, I was able to locate a damaged or high-resistance cable that was connected to pin 4 of the swirl motor connector, which is the positive PWM feed. I'm currently looking for replacement pins so I can make the necessary repairs.
Aspiring that this information proves useful to someone going through swirl flap trials.

Great, I'll be able to put this information to good use.

We have fixed the major issues with these engines, so your car will last for many years.

Thank you for the post and the excellent detective work!

In order to prevent others from delving too deeply into the om651 beast's guts, I wanted to demonstrate that it's not just mechanical on the swirl flaps.

I foresee the connector and its cables becoming a common source of failure due to their high level of vibration.

Previous testing, specifically fat meter probes that flared the female side of the connector, has been the object of my blame for these poor connections for years.

Recently, I've been 'cleaning' and sealing the ECU connectors on my Viano (OM651). However, you'll have to resign yourself to the fact that corrosion is more likely to blame than fat probes.

I am uncertain if these connectors are coated with anything protective, perhaps silver, to prevent that.

Back probing this type of connector when fault finding is considered the "industry" standard, though I am not an electrician.

It amazes me that there aren't more problems because I've seen the om651 in my car shake the engine.

Reverse probes? Currently, I prefer to use needle-type probes that insert smoothly.

Despite the 651's misleading marketing claim that it is smoother than the 646, the vibration suggestion is entirely reasonable.
However, vibration between connections should be reduced by the entire plug-in assembly, including the ingress rubber seals. The connectors fit snugly and securely. The female could flare up at some point, though, and you're probably right about that. Without a doubt, I've witnessed numerous unreliable connections and made the unnecessary replacement of bits due to diagnostic errors.

Please clarify if you are asking to test the connector from the rear or the wire side. My apologies, I just realised that.
I usually check for continuity by disconnecting one or both ends. After I've established that the sensor is resistant, I can test the other end of the wire to see if it reveals a bad connection; however, this isn't necessarily conclusive because the connection could be unreliable.