Irreparable intake air leak.

[clk320x4]

Greetings to everyone

I own a high-mileage, 460,000 km W212 E250 CDI used for a chauffeur service in Australia.

A few months ago, while driving home, I had a little bump followed by a loss of power, an illuminated engine management light, and a soft limp mode. I was able to drive home but had to manually shift gears.

Previously, the boost hose had split, exhibiting same symptoms; thus, I assumed it was the same issue and was able to restart the vehicle without applying sufficient weight to activate limp mode.

The attempt was unsuccessful, so I brought it to a mechanic, who scanned it and retrieved the MAF code and gearbox code.

Cleaned the mass air flow sensor, no results; replaced it with a non-OEM Vemio sensor, still no results.

To summarise, we are essentially making random adjustments, having replaced the mass airflow sensor, another intake sensor, the EGR valve and cooler, two intercooler hoses, the intake manifold and this week, the PCV cover.

The vehicle idles smoothly without any discernible unusual noises.

If the PCV does not resolve the issue, we are both at a loss about the source of the air leak. The new MAF has been recalibrated, so any insights or comparable resolved cases would be very appreciated.

Salutations

[developer]

I would have suspected the boost hoses; however, you have replaced them. Conduct a smoke test to identify any leaks.

[clk320x4]

Having completed that, there is no observable change. I have replaced all recognised common components that might trigger the issue code. The PCV is now in progress. Are there any unusual components or circumstances that can result in an air leak? P227906

[clk320x4]

All replacement components are from recognised aftermarket manufacturers.

[bvlenci]

Considering the high mileage and warm environment, my first idea, apart from the boost system, was that the EGR or intake manifold may have deteriorated.

However, if a smoke test reveals no smoke leakage, I can only conclude that it is not a boost leak. A sensor is the rational choice.
Have you examined the DPF pressure sensor and associated lines? The component is sufficiently inexpensive to warrant replacement if it has not been done before.

My E350 exhibited problems without consistently generating error codes. I am uncertain about the similarities between the two engine systems, unfortunately.

[clk320x4]

Have rebuilt the EGR and intake manifold with little impact; now changing the PCV and will investigate the DPF sensor.

[bvlenci]

It is widely advised to purchase authentic parts for the E350. However, they are manufactured by Bosch. When purchasing a Bosch product for around £30, it is advisable to get it from an authorised distributor, such as a Bosch diesel centre, to ensure its authenticity and fresh condition.

I acknowledge that yours is the 250, but I own 350 experience.

[John278]

Hello, I am experiencing the same problem here. I have replaced all the components you specified, and no intake leak was detected during smoke and pressure testing. The vehicle is a W204 OM651 220CDI. Mileage: 220,000. The DPF has been regenerated, and post-regeneration, the DPF fill level is at 15%. However, after driving 100 km, it increases to 55%. The greatest pressure differential at full speed is 270 mbar. The problem is not persistent; it manifests only sometimes. The injectors have been removed and are presently on the test bench, exhibiting comparable results. Any suggestions?