E 320 Diesel Code P0471 - PeachParts Mercedes-Benz Forum

nyko46 · #1 03-29-2020, 02:11 PM

Not long ago I posted a thread related with a problem that I had with my 2008 E320 Bluetec related to a DPF restriction: Code P242F
I also mentioned that my glow plug control module was bad and after replacing the control module the "engine light" was cleared by itself, and the car started running good as before any code.
This week I had again the engine light back with two codes: P0471 "Exhaust Pressure Sensor Range/Performance" and code: P242F : Diesel Particulate Filter Restriction - Ash Accumulation".
My question is about the sensor in subject. Is this code telling me that the sensor is bad or the DPF is affecting the sensor functionality to not perform well?
Also previously I mentioned that I drive this car 54 miles in highway everyday and there is not reason for the regeneration not to work properly if the DPF is really restricted.
Even now with these codes the car drives strong with not hesitation and the fuel consumption is very good 33 - 35 MPG
I will appreciate any explanation regarding this issue.
Thanks

I

pawoSD · #2 03-29-2020, 08:07 PM

That code is telling you that the DPF is plugged and therefor triggering the Exhaust pressure sensor as the back pressure is too high, so the sensor is doing its job correctly and is probably fine. Its the DPF most likely in need of cleaning/replacement.

nyko46 · #3 03-29-2020, 08:10 PM

Quote:

Originally Posted by pawoSD

That code is telling you that the DPF is plugged and therefor triggering the Exhaust pressure sensor as the back pressure is too high, so the sensor is doing its job correctly and is probably fine. Its the DPF most likely in need of cleaning/replacement.

Thanks for your reply.
I was not sure if that code was about the sensor or about the DPF

engatwork · #4 03-29-2020, 08:18 PM

Make sure you clean the cat and DPF. How many miles are on it? I've had one in shop (09) that had a leaking o ring on the plastic piece at the throttle butterfly resulting in oil being pulled into the passenger side air filter inlet resulting in, I suspect, plugged dpf. What kind of oil have you been running in it?

nyko46 · #5 03-29-2020, 09:31 PM

Quote:

Originally Posted by engatwork

Make sure you clean the cat and DPF. How many miles are on it? I've had one in shop (09) that had a leaking o ring on the plastic piece at the throttle butterfly resulting in oil being pulled into the passenger side air filter inlet resulting in, I suspect, plugged dpf. What kind of oil have you been running in it?

It has 120K miles and I use a Valvoline1 5W30 synthetic oil.(not blend)
My DPF was cleaned 3 months ago but according with the mechanic, it was not possible to have it completely clean. I have not noticed oil leakage and never had to add oil between oil changes.
As I said, after mechanic cleaned DPF the engine light still on and was cleared only I replaced the Glow Plugs Control Module.
Since then there was no engine light until now.
Thanks

pawoSD · #6 03-29-2020, 10:17 PM

Valvoline1 5w30 is not a diesel rated oil, and not a low-ash diesel rated oil....you need to be using something that meets the MB 229.51 or 229.52 specifications or the DPF will be steadily destroyed.

Examples are Liquimoly https://products.liqui-moly.us/oils/longtime-high-tech-sae-5w-30-1.html

Or Mobil 1 ESP Formula M 5W40

I use the liquimoly and it runs great, oil analysis results show it holding up perfectly for 6-8k miles in my OM651 diesel with a DPF system.

engatwork · #7 03-30-2020, 05:50 AM

Make sure you use a diesel rated oil with the additional ESP rating. Pay close attention to what got "cleaned". There is something called a DPF that has to be cleaned AND you will find that the cat is probably plugged too. I forget but one is closer to the engine and then the other is the next device downstream. I had a customer in with 09 with same issue, DPF had been replaced but the cat was still plugged.

engatwork · #8 03-30-2020, 06:01 AM

Both the muffler looking thing and the "can" to the left will need to be cleaned out.

pawoSD · #9 03-31-2020, 09:53 PM

The rear unit is the SCR (selective catalyst reduction) unit...it is where the adblue is injected and the reaction happens to reduce nox to nitrogen.

jay_bob · #10 04-01-2020, 07:44 AM

The OP has a 2008 E320 BT. Same year/model car that I have. No SCR on this vehicle even though the trunk says "Bluetec". (Same year/model car in other parts of the world have CDI on the trunk.)

However the other statements made above about oil are absolutely true. If you use regular oil in this engine you will destroy the DPF. Thus the reason for the warning label on the right air filter near the oil filler that tells you which MB specification sheet oil to use, and a label across the radiator support that warns against never using any non compliant oil in the engine or it will damage the exhaust system.

pawoSD · #11 04-01-2020, 11:05 AM

Interesting, I guess they were just testing out the Bluetec badges ahead of time

engatwork · #12 04-01-2020, 04:57 PM

Yep