Engine Light, Fault Codes, 2013 313 Sprinter (L3/H3)

[Doc.]

Hi all.
Not been on here since just after my Daughter bought the Van (July 2021).
She was going to do a Camper Conversion, but then my first Grandchild came along, so that's been shelved.
It's not done a lot of miles since she got it, mostly me borrowing it for moving Motorbikes and DIY stuff around!

Anyway, it's just thrown the Engine Check Light.
My Topdon Diagnostic Tool shows the following DTC;

P2BAC ~ NOx Exceedance - Deactivation of EGR (both 'current' and 'stored' Codes)

Also, a System Scan brings up the Code;
P010315 Mass Air Flow Sensor 1 has a Short Circuit To Positive, there is a Circuit to Positive or an Open Circuit

I took it off and gave it a quick clean today, no change. Wasn't expecting it to rectify it, but thought it was worth a try.

12V at the Connector is good, as is the Ground/Earth.
I haven't done a Voltage check on the other Pin(s) to see if it changes with Revs yet, that's the next job.

Any 'quick' checks I can try, like running with the MAF disconnected?
Any other related areas to look at, Intake leaks, wiring damage?

Is the NOx/EGR fault likely to be connected to the MAF Fault?

Many thanks for your time.

 

[supernoodle]

The NOx Exceedance - Deactivation of EGR fault is just a statement of fact. It is telling you it has deactivated the EGR, therefore the NOx will be increased.
The MAF is the feedback in the EGR closed loop control system. So if MAF signal is missing it can't control EGR, so it gets deactivated.

Mass Air Flow Sensor 1 has a Short Circuit To Positive, there is a Circuit to Positive or an Open Circuit, is a simple electrical diagnostic check, it suggests the ECU is seeing a constant 5v at the signal pin, nothing to do with air leaks.
You need to check the sensor output, check the wiring between sensor and ECU,

 

[Doc.]

OK, thanks SN.

Is it a fairly common/known fault, and if so, what's the usual culprit?

I'll check the Sensor output as soon as I can, thanks again.

 

[Doc.]

Had another play today.
I've been doing some other work on it due to a Coolant Leak (it was the Seal on the Fuel Filter Housing.

While I had everything stripped off to get to that, I stripped the EGR Assembly, back to the Joint behind the Engine, cleaned everything up, reassembled.
Removed the DPF (as it also has the 'Exhaust Filter Blocked, Drive at High Engine Speed' message), Blanked the aft end, and the Sensor/Hose Ports, and treated it to a 5 litre dose of Wynn's DPF Cleaner, left it overnight.
Flushed it through, but was only getting a Trickle through, both directions, no amount of flushing would improve it.
Gave it another overnight soak with another 5 litres of Wynn's.
Much better, flowed fairly well in the 'normal' direction, took a while to flow properly in the reverse direction, but got there in the end.

Ran it today, message still there, still in 'Limp' Mode . . .
Also took a look at the PCV Valve Diaphragm, as there was a lot of Oil over the lower Intercooler Hose, and in the Intake Manifold and Hoses.
Diaphragm is fine though, clean and flexible, no damage, so where is all the Oil coming from I wonder?

Is there anything else that can go wrong with the PCV System?

I did some Electrical checks on the MAF Sensor.
With the Plug disconnected ~ Ign 'on';
Grey/Yellow =5V
Yellow/Brown = 0V
Purple/White = 12V
Pale Green/Yellow = 5v

Plug connected, hot Engine, Ign on;
Grey/Yellow =2V
Yellow/Brown = 0V
Purple/White = 12V
Pale Green/Yellow = 2.5v

Plug disconnected ~ Ign 'off'
Grey/Yellow = 2.2kΩ to Earth
Yellow/Brown = 0.7Ω to Earth
Purple/White = 1.7kΩ to Earth
Pale Green/Yellow = 5.1kΩ to Earth

I've read elsewhere that it's possible that the MAF Sensor can be good, but the ECU will throw the code (MAF Short Circuit To Positive) to put it into Limp Mode?

Could I be chasing a fault with the MAF that's not actually there maybe?

All Fuses are good, went through them all again today, under Driver's Seat (RHD Van), and in front of the OBD Socket, L/H side.