P2bac

2014 MERCEDES BENZ SPRINTER

407,000 MILES • 2.1L • 4 CYL • 2WD • AUTOMATIC

DUKEBOY

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Hi,

I’ve been trying to sort this problem for years and a lot of money. It started with a check engine light boost pressure deviates from specified value) the van would go into limp mode but after cycling the key it would run great. I mainly drive freeways. So far, I was told it was the turbo actuators so replaced. Didn’t work. Still same. Took it to another mechanic said an EGR delete would fix it. Did not fix, the bug caused more problems as the tuner didn’t know how to fix. So, I went to another tuner now van drives great but still goes into limp sporadically. Took to Mercedes’ dealer. Told it was the 02 sensor on exhaust. Replaced but still no change. I plugged in my Bluetooth OBD reader and came up p2bac.
I’m just about to just let it keep doing it and live with it, but it just irritates me every time.
Thanks

Jun 8, 2022 at 6:50 AM

KASEKENNY

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18,907 POSTS

This code is a NOx Exceedance code which deactivates the EGR causing the engine to go to limp mode.

https://www.2carpros.com/articles/reduced-power-limp-mode

A couple of questions with this, now that you have deleted the EGR you need to either undo that alteration or find a tuner that is capable of having the PCM ignore this code as well as the other emissions codes that you get with EGR issues.

However, the likely cause of this is the fact that the engine is producing too much NOx and so it forces the engine to limp mode. What this means is, NOx is a harmful emission that is a byproduct of diesel engine combustion, and it can no longer be emitted to the atmosphere.

If you remember when trucks would put out black smoke, that contained NOx.

So, the PCM on your vehicle thinks that the engine is producing too much and so it shuts it down.

This means you have either a mechanical issue and you truly are producing too much. This would be sticking or damaged injectors dumping too much fuel. So, when was the last time you changed your fuel filters? This is crucial with diesel engines so if you have not changed them then you need to do that. More than likely if the injectors are damaged so this will not fix it but if they are not then that will prevent them from being damaged.

Next, we could have a faulty Oxidation Cat Converter. This is the converter that will convert the harmful emissions into non harmful. Basically, it has a ceramic coating that has a chemical reaction with the NOx and changes it into non harmful emissions.

However, if you can restart the engine and this does not reoccur then this is likely not the issue.

The PCM may think it is due to the sensor failure which is what I think this is. So, when they replaced the o2 sensor, what was the part number?

Let's start with this and go from there.

Thanks

Jun 8, 2022 at 4:19 PM

DUKEBOY

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Hi Kenny. The 02 sensor part number is 003 542 18 or 16. I replaced it with a non-genuine part, but Mercedes coded it into my ECU. It didn’t stop it. I saw that it looks like I have an injector seal leak. I’ve attached pics. Also, the 02 sensor was replaced.
Thanks

Images (Click to enlarge)

Jun 11, 2022 at 7:40 AM

KASEKENNY

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Interesting. Clearly, we can't have a leak, but I am not sure this is the cause of the NOx code. However, we need to fix what we see and then retest.

So, I would repair that and go from there because I can make the case that it could cause it.

Jun 11, 2022 at 10:53 AM