G and AdBlue

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Jdring
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I'll start this thread - there have been a few about AdBlue over the years.

I have a G350 with the OM642 V6 3Litre engine, and AdBlue.  First time with AdBlue and asides from the hassle of occasionally having to add 10Litres at a small cost of £15 ish, it seems a good idea (inject urea into the exhaust system to convert most of the NOx to N2 and O2 again - less smoke, less EGR needed and enables the G to reach Euro6 levels of efficiency - needed for some city driving, increasingly.  

But AdBlue means more sensors and in an electronic G its always the electronics that get you, because unless you carry around a STAR system there is not much you can do to bypass errors that crop up.  So compared to my mechanical 460, this 463 with AdBlue is already throwing up some occasional dashboard messages!

So the AdBlue message now is that it thinks I need AdBlue, but when adding it, I got to 7Litres and it overflowed all down the side of the G.  Not good - have to wash that stuff off.   Note the theory is that AdBlue is added by the garage at services, but how they know how much to add is a mystery as there is no level indicator, until it spills out!

Then you get the follow up message that without AdBlue topup, you will not be able to start the car in 800miles.   But then the message goes away (zero messages in the COMAND Settings view), only to come back again when you restart, and the timer starts again at 800miles.  Once it said 2400 miles!

The problem came on a long trip, cruising at 80mph+ if that adds any insight.  I am thinking that at those speeds the AdBlue delivery systems is working hard ?

So it looks like a MB visit to me, to check/replace a sensor, or possible the AdBlue delivery pump/system.  

Anyone know anything to try to isolate the actual issue?  Checking something in the COMAND Engineering view for example?

Or got diagrams of the G350 Adblue components? 

bigblock
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Re: G and AdBlue

John

My experience with a GLE, Evoque and Ford Ranger using AdBlue is that it can sometimes take a few driving cycles before the system resets correctly and the warnings stop appearing. On the GLE I found that if I turned the ignition on for 30 seconds and then off two or three times after I had refilled the AdBlue it would solve the problem.

 

Pistonhead
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Re: G and AdBlue

I don't think a disconnection is likely to be an easy fix as the computer is invloved. I have no doubt that it would have some sensor parameteres to look for and anything out of the range would flag up an engine stop light. That is unless if some has on the after market a reprogrammed ECU values.

There is another point not mentioned above, if the vehicle's Ad Blue reservoir is low the stop light will come on initially upto a point if you push it  the engine refuses to start untill the reservoir is replenished and the whole sytem has to be reset using Star or other generic kit would do it too. I have a feeling that low fuel could affect the reset as the DPF is designed to complete a self regeneration with at least that much fuel in in it to complete the cylce - but not 100% certain of that point.

Jdring
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Re: G and AdBlue

Thanks Rakesh.

The AdBlue never completely ran out.  The first time it was re-filled after just a few dozen miles and the alarm went away as expected.

The second time. much earlier than expected and whilst cruising at speed, the AdBlue low alarm came on, and after about 150miles (should have 800miles range at least) I topped up with 10L to find that it overflowed at 7L.  The Check Engine light is on and it re-warns every time you start the car, after about 2-5 minutes.   Then after a couple more days, the warning stopped appearing one time, but the Check Engine light remained?

I played today with OBD Plus, an App with an OBDII reader - not recommended - fairly rubbish, and it reported 4 faults. (P43AA, P43A8 twice) But it seems to find a fault each time you run it anyway (I got U4003 and P1303 once). 

I tried clearing the faults, and after multiple attempts 2 of 4 cleared and then, when I next started the car (just now) there is no more Engine light and no more AdBlue warning.  Its gone away.

It will be Serviced on Monday, and will take a look with STAR at the history.

Maybe it was complaining/confused about being over-full.

Pistonhead
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Re: G and AdBlue

The fault codes you have showing are fuel and, or misfire in No:3 cylinder and the 'U' indicates an emissions fault relating to low AdBlue. This understandable but the misfire should not be AdBlue related it could be now and then you do actually have a misfire.

When were your spark plugs last renewed? Do Check on that history, if you have done the miles change them. Failing to change the spark plugs when due pust additional stress on the coil and eventually this burns out. This is the most common cause of failure for coils on plugs.

Theo
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Re: G and AdBlue

Diesel engines have spark plugs?

Jdring
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Re: G and AdBlue

Update:

MB Indie (Griffiths in Reading, very good) checked it over.  They had similar before with BlueTec (ML).  They updated the out of date ECU software.  Apparently, this modifies how 'tolerant' the checks are before throwing the exception.  Its likely not measuring the level of AdBlue, but the NOX sensors in the exhaust.... if they decide that not enough NOX is being neutralised, it throws the alarm up.  You can reset it (with OBDII) and it goes away til the next instance.  It explains why I have seen it mostly cruising at speed - more volume of NOX and sensors more likely to decide its too much.

So the new sw should stop it popping up.

There are also new (gen 2) NOX sensors available, but they are not cheap (£300 each, x2) and mine are not showing any faults... they are just more sensitive in v1.

All good.

 

 

 

Pistonhead
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Re: G and AdBlue

Theo wrote:

Diesel engines have spark plugs?

Sorry, I did not check when making my comment - and you are correct  Diesels don't have spark plugs. Could be Injector or Injector wiring issue,

Jdring
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Re: G and AdBlue

Pistonhead wrote:

Theo wrote:

Diesel engines have spark plugs?

Sorry, I did not check when making my comment - and you are correct  Diesels don't have spark plugs. Could be Injector or Injector wiring issue,

I've had injector cleaner added in this service.  The P1303 error only appeared once.  Not concerned with this.