Faulty Ad Blue Light & Pricey Diagnostic Test - Advice Needed
 

Had our 2010 GL350 B serviced by our independent guy who was alarmed our Ad Blue was so low. The truck's "low adblue" light never went on.

Because he prefers not to do the computer stuff, he asked us to go to a dealer to have the indicator checked. We have an extended warranty through MB USA.

Took the truck in today and the service rep is telling me it will cost $160 to run the diagnostic test to see if the indicator is working properly and that the diagnostic test is NOT covered by our extended warranty.

Does this sound right to anybody?

TIA. Posted this on the other forum, but someone suggested I post it here too.

they are charging you for one hour of labor. so the $160 part sounds right.

warranty warrants broken things. your adblue light/indicator/sensor might or might not be broken. if they troubleshoot it and it is ok- you pay out of pocket. if they troubleshoot and it is broken- warranty pays according to terms.

How many miles did you put on your GL since the last Adblue fill? Who filled it?

I'm just asking because I have now found 3 separate instances of the dealership forgetting to service my Adblue tank. I was able to figure out they weren't filling the tank by listening for the urea sloshing around after leaving the dealership. If the tank is full, you shouldn't hear any sloshing.

I think the typical usage (if your tank is topped off) is about 5 gallons per 10,000 miles. If you tow a lot or have a very heavy foot you could be using more but still you shouldn't be using anywhere near the 8.3 gallons the tank holds after driving only 10,000 miles. I don't exactly baby my GL and I know from filling it myself that I use roughly 5 gallons over 10,000 miles. I also idle my engine a lot. If someone were easy on the throttle and didn't pull anything or idle much, I could easily see the urea tank getting to 20,000 miles or very close to it.

The point is, if your tank is being serviced as scheduled, you really shouldn't ever be worrying about it running out.

43221B, thanks for your reply. I follow a lot of your diesel posts.

In addition to our independent adding AB, we typically do the AB ourselves. Sometimes, we even provide the AB for him if we have extra. We've started to buy the smaller bottles in addition to the larger ones to make it easier to top it off. I probably should have popped another bottle in there before I waited for Service B, but figured I was safe as long as the light didn't come on. Well, the light never came on and our service guy was pretty alarmed because it was quite low.

We're putting about 20k on the car per year. I can tell when the tank is a little low even before the light comes on because the engine seems to idle a little rough. It's subtle, but I notice it.

I agree, if we just keep it topped, there shouldn't be an issue, but was wondering if anyone has had a similar issue of the indicator not working and if there was an alternative to running the diagnostic.

Thanks.

no, you cannot. engine idle quality (or ignition @ any throttle angle for that matter) has zero to do with the piss injection (or lack of)

I had a similar problem on my 2011 GL350. At around 30K miles the AdBlue light went on even though the AdBlue tank was about half full. The Mercedes dealer said the light went on due to inferior quality AdBlue (I have been refilling the tank myself with AdBlue that I buy at AutoZone since the dealer rips me off for $280 to do 15 minutes worth of work). I was charged $300 to diagnose the problem and flush and refill the system with Mercedes AdBlue (which shouldn't be any different than the stuff Autozone sells- just a lot more expensive at the dealer).

Then, a couple of weeks ago I brought the GL in for service D. I decided to let the dealer refill the AdBlue since they offered me a "deal" if I prepay for the next 3 services (only $1,200 which seems like a good deal since I seem to be laying out almost a grand every time I drive in there). Literally two days later, the AdBlue light and the Engine light came on. I unscrewed the cap to the AdBlue tank just to make sure the tank had been refilled, and it was full to the tap. So I brought the car back to the dealer and they said it was a faulty sensor and replaced the unit (which makes me wonder if the AdBlue problem I had the first time was really the sensor and not the quality of the AdBlue I put in???). That was about a week ago, but guess what, the AdBlue/Engine light went back on again yesterday. So now the vehicle is back in the shop again. At least the work is under warranty and I get a free car wash and Mercedes loaner to beat on. And the dealer is nice enough to pick the GL up from my house and exchange it for a loaner. So I'll let you know what the new diagnosis is in a couple of days.

Also, I'm glad I bought the extended Mercedes warranty when I purchased new - 6yrs 125K! I'm sure it will be worth the $4K I laid out

Wow. They'll pick up your car and drop a loaner?!? Who's your dealer?

And yup, makes me glad I got the extended warranty, though I think I could monitor the level myself. They also fixed the defective sunroof switch under extended warranty that would have cost $800 according to the invoice.

Also, any comments about different qualities of AdBlue? First time I've heard that one.

Alx, do know how else to explain it. I've filled my AdBlue before when has indicated in the past and immediately the engine sounds better and the idle is softer. Could be a coincidence more than three times, but I doubt it.

I dont think there's a difference between AdBlue or any other DEF since the solution is standardized. I use BlueDEF. According to wikipedia:

There is a mode in the instrument cluster that you can put it in and it'll show you bars on how full the adblue is.. looks like - - - - -

Not sure what DEF you have been buying at Autozone but they sell PEAK and that is the same brand that I watched the MB tech put in my GL at the dealership. I think I would have disputed the "inferior quality AdBlue" claim. Personally, I think that claim is about like saying that MB isn't going to cover a bad windshield washer fluid pump because you used inferior washer fluid. I would say, prove it.

FYI, the service advisers get paid more commission for work done out of warranty than they do on warranty work.

all piss is the same...

the softer idle - i have no idea. even in theory the level of piss in the tank should not have an effect on idle quality...

How do you get into this mode in the instrument cluster? I have looked in the manual but no mention of it. thanks

BTW, my AdBlue/Engine light went on again yesterday after a fourth attempt by the dealer to fix it. The first time, they said it was faulty AdBlue and flushed they system. That worked for a few months. Then I brought the GL in for Service D and the light went on the next day. They said it was a faulty sensor and replaced it. The next day, they AdBlue/Engine lights went back on. This time, the dealer said they located a pinched wire and supposedly fixed it and test drove it 100 miles to make sure it was fixed. Two days later, the light went back on - now back at the dealer awaiting repair again!

You want to put it into the Engineering mode and then you can scroll through.

https://mbworld.org/forums/m-class-w...ght-reset.html