kpnewman88

Hi everyone. I completely love the forum but do not post often. Sadly after having my car out of action for 4 months I figured I would reach out to better minds.

Car is GL350 2012 Blutech with OM642 engine ~122,000 miles. Car has had the emissions recall done.

I was driving at highway speed when the car engine completely died, just cut out entirely. Kicking myself but did not pull codes at the time, or check battery voltage. (I think it didn't even crank at the time of failing).

By the time the car arrived home from the towing company the battery read 7v, pretty much every module had a low voltage code. Only other code was a permanent NOx fault P229F 'NOx sensor circuit range/performance bank 1 sensor 2'.

Question 1 - My understanding is NOx sensors going bad get you a 10 start countdown, has this changed post emissions recall? Both sensors read 65535 ppm now while trying the crank. Haven't replaced sensors as under Mercedes warranty, and didn't think it would stop the car running based on all the readings I've done.

Car will crank now and even try injecting fuel, but doesn't seem to get above 300rpm ever. I don't see smoke coming from exhaust and even took exhaust off turbo trying to see if engine was actually combusting, if it is it's only a little.

Question 2 - Strange things I'm noticing in my live data while trying to start:
MAF sensors both stay at 0g/s while cranking - would MAF sensors pick up flow at 200rpm?
Fuel flow reads 2.4L/hr - is this too low?
Exhaust pressure sensor bank 1 reads 0kPa. - What sensor is bank 1, I would imagine it should read ~100kPa?

Question 3 - If there was an immobilizer triggered from the towing activity, would a warning/code be visible (on dash or code reader) or would it just block the successful start?

Bit more background in things I've done:
Checked injector leak off - two were out of spec so replaced
Checked resistance of glow plugs (all 0~.7ohm) but wouldn't have caused the cut out at highway speed

Replaced the following parts:
Fuel rail pressure sensor
Fuel rail PCV
Fuel pump PCV? and safety valve
Exhaust pressure sensor (near turbo)
Cam sensor and crank sensor both replaced
New battery
Drained all diesel and refilled with different fuel incase of contamination.

Running an Icarsoft MB v3 scan tool, so not as good as mercedes star, but better than a generic. Fuel rail pressure is keeping up with demand signal on scan tool.

My thought is most likely the car has an electronic block to start somewhere, hence all the sensor replacements. Failing that potentially air flow to engine is restricted?

kajtek1

You might want to move the topic to diesel section for better exposure.
Modern diesel can only die due to lack of fuel, or electronic issue, when in your case sounds like the 2nd might be the truth.
Low battery after tow can be contributed to different things and since you did not check it before towing, we have to guess.
At this point I would:
-get new battery
-get new fuel filter
-get new air filter
-clear all the codes and confirm they are clear after cycling the ignition
-start the engine and read both fuel pressures.

kpnewman88

Hi kajtek,

Thank you for the reply.

Have already done all those things. NOx code does not clear, everything else does. Fuel pressures are as requested by ecu. ~1250kPa from low pressure pump and 24500kPa from high pressure pump (this increased to 50,000kPa while cranking).

Keith

kajtek1

I don't see Nox sensor on your replacement list? When your car should not require SCN coding, the new sensor might still need coding. You need @Deplore help with that.
Checking the fuel 1250 kPa= 181 psi.
I did not work on fuel system that much, but low pressure usually is reported at 60-70 psi.
Than your high pressure is on low side.
Solve the Nox issue 1st and see if it will run.

kpnewman88

Hoping to get confirmation that a NOx sensor will result in car completely stopping without a warning counter? It’s covered under warranty but a tow to Mercedes is around $500 and I am pretty certain it is not the primary issue.

kajtek1

I don't see you posting location, but MB USA offers free roadside assistance to qualified owners, where warranty qualifies.