W212 P24AF- Particulate Matter Sensor
 

Have been away for a while after selling my 1999 W210 OM606 with 348k miles since I bought it new. The newer car is a 2014 W212 with 4 cylinder twin turbo. I bought it in 2014 as a MB dealer's demo with 4k miles. Now at 101,000 miles and I am getting a CEL (OBDII) code of P24AF. This seems related to a "Particulate Matter Sensor". Does anyone on the forum have experience with correcting this one?
Thank you,
Ken

Find an exact description of the code, this will help diagnosis greatly.

( RE: is the sensor wire broken, pulled to ground , pulled to power , failed sensor. Codes are pretty specific as to that the computer is seeing that it does not like. A code is not always an indication that a particular part needs changed. )

P24AF Code- Particulate Matter Sensor
 

I will see what I can find on code detail. The car was at the dealer on Friday (2 days ago). I was already up to $550 for a B-service and they wanted $330 more to hook up the scanner and read any stored codes. Will see what I can figure out before going the dealer route.

This W212 E250 turbodiesel model has the 651.924 engine.
Thank you,
Ken

Scan Tool Thoughts
 

Different question related to the original post.
The 2014 W212 E250 Turbodiesel 4Matic has just 101k miles on it. The last car I drove 348k miles over the almost 16 years I had it so I figure I will keep this still new one a long time.

With this current OBD code issue and the dealer looking for >$300 to hook up their scanner I am thinking of buying my own code reading/diagnostic equipment with more complete capability than the basic OBDII reader I have now and use mainly on my old truck. Have heard about MB XDOS readers. Any recommendations appreciated.
Thanks,
Ken

Either purchase ebay clone or if you are good with troubleshooting you can probably get by with an Autel brand system.

IIRC there are a few different types of sensors on the exhaust system - pressure differential sensor, temperature sensor and O2 sensor, etc.... Pin down exactly which sensor you are getting reading on and get back to us.

Codes with upgraded reader
 

I received the iCarSoft MB II tool and updated it to current version software early this morning. The codes I get from it are:

U103888

and a separate message that "B1-S1 Sensor Heater Fail"
0.001V Actual, 0.110V Max

Any suggestions appreciated on what this points to as an issue on my 2014 E250 Bluetec 4Matic @ 102,000 miles. The car drives as normal with no apparent problems.

Thank you,
Ken

The U code is a "Bus Off" error. The other code is implying you have a bad O2 sensor heater circuit.


A cursory Google search reveals that Daimler indeed is using O2 sensors on the emissions system of your car.


I would replace the O2 sensor or the particulate matter sensor on bank 1 sensor 1, reset the vehicle, and see if that solves it.

This might not be an oxygen sensor but an oxides of Nitrogen sensor.

Did the P24AF show back up on the new scanner?

I was going to suggest the MB II. I have one, and it does most everything needed for these cars.

Yeah that's what I thought too. I was scratching my head until I saw this:


Https://mbworld.org/forums/r-class-w251/651880-e320-bluetec-o2-sensor-locations.html


Beats me!

Sensors
 

The iCarSoft MBII did not turn up the P24AF code. When I asked at the MB Dealer what this code means they said they had no idea and that it was a generic OBDII code with no meaning to MB.

It seems there are two sensors that could be the root cause of the warning light and why I can't get through NJ State inspection. The car runs as great as it always has.

The differential pressure sensor is part A642 905 02 00. It is available at a price range of about $30 up to $108 at the MB dealer.
The nitrogen oxides (NOx) sensor is A000 905 35 03 and is available from about $240 on-line up to $560 at the MB dealer.

Before I spend money in throwing parts at this I will remove the engine cover and look around carefully to see if there is another obvious cause...such as a broken wire, loose or dirty connector, etc.

Onward!

Please keep us posted as to outcome.

Calling the dealer or independent shop for " I'm fixing my car and want you to help me for free " is bad form.


Don't guess, diagnose based on what you are seeing on the scan tool. There are hundreds of trouble codes that can turn on the check engine light.

You need a wiring diagram / trouble shooting tree to test the B1-S1 sensor. From the scan data it appears that the

you are getting is measuring voltage across a shunt resistor to calculate current. With no voltage drop across the resistor, there isn't any current flow, this tells me that either the heater is burned out or it's power supply is zero.


Never throw parts for an initial diagnosis / repair attempt, that is reserved when there are parts that can't practically be tested in the field / have gone slightly off scale.

Doing a general look over is always a good thing, you will likely need to get under the car for the NOx sensor, they generally have the electronics permanently tied to the sensor wire.

Given you apparently don't have a code for the differential pressure sensor, why are you considering replacing it?

Update
 

Wow, much was inferred/assumed based on a relatively simple question.
The question of P24AF meaning was asked of the dealer service department while the car was at their shop getting a $550 oil change (5/5 post). People are always looking to get something for free in my own business and I would not stoop so low.

No apparent wiring issues upon my further inspection. The car is going on the dealer's STAR Diagnostic system tomorrow.

Will keep everyone posted on how it sorts out.

Actually the XENTRY diagnostic system.

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