mihir_d

I had my CATs replaced recently under the 8 yr./80000 mile CA emissions warranty.

After that my mileage dropped significantly so I took it back to the dealer for inspection.

Here's the outcome:
Voltage on Mass Air Flow Sensor (MAF) out of spec. MAF needs to be replaced. Cost $500.

I did some research and the most common cause for MAF failure is a leaky exhaust...

With the CATs having failed on my vehicle there is no doub't that my ML's exhaust was leaking for a while...now the dealership tells me that although the CATs were covered under the CA emissions warranty, the MAF won't be, although it is obvious that the MAF failure was a result of the CAT failure.

I am planning to fight with the dealer to cover this repair under warranty, since it is obvious that the CATs are defective on this vehicle...since I have heard tonnes of stories of CATs failing on this vehicle....

The other thing, I found to watch for, with a leaky exhaust is spark plugs. A leaky exhaust shortens the life of spark plugs.

I am now even questioning whether the CAT failure did any more damage than just the MAF and possibly the spark plugs...it won't be surprising to realise that there is possible more damage done by CAT failure...

Anyone on the forum has got the MAF covered under the CA extended emission warranty? Just wanted some advice on how to approcah MB with this.

I seriously think, this car is a piece of expensive junk...its critical components are failing one after the other in just 3-4 years of ownership...wonder what's more in store with this...

sosh

The MAF sensor, the spark plugs and even the Cats are consumable items on this and every other car. Some last longer than others but they are consumable. I do not know where you get the idea that an exhaust leak can cause plug and MAF failures??? Looks like you wish to drive for nothing

mihir_d

And I'll find you the other one that puts the blame on the CATs for the MAF sensor.

azinn
Almost a Member!

Registered: May 2003
Location: The Sunshine State
Posts: 46
Dealer replaced my plugs along with the MAF under warranty on my '00 ML430 last week at 46,000 miles. SA said plugs need to be replaced when MAF is bad, I guess they get dirty. Truck seemed to run okay to me

https://mbworld.org/forums/showthrea...&highlight=MAF

Here's an instance of the MAF sensor being replaced under 100000 miles for a 99 ML430 - that was in Canada though...not sure about the states.

Drummberboy, if you are there, can you elobarate on the specifics of how you got the MAF replaced under 100K under warranty?

drummerboy
Junior Member

Registered: Sep 2003
Location: Edmonton
Posts: 13
That's not under warranty? I thought it was considered a major component. We had discussions with MB over this! 1999 under 100Km.
Don't know how it works in the states.

https://mbworld.org/forums/showthrea...&highlight=MAF

redcoupe

MB will replace your MAF under starmark warrenty, which is up to 100k miles.
I can see a exhaust leak setting MAF sensor codes(mixture formation at limits), but all that is needed is the fuel trim to be reset(selfadaptiosn), because if you dirve it with the leak it leans out the fuel trim.

Brian

mihir_d

I understand...I don't have the starmark warranty so guess, I shouldn't be complaining about MB not covering it and my having to pay for it.

I don't have any codes set on my OBD yet, by the way. It was only through watching the mileage on the overhead trip computer did I realise that my mileage had dropped significantly.

After going through your explanation, what I am considering doing now, is to get the self adaptation reset before taking the vehicle back from the dealer (I had left it at the dealership for diagnostics over the weekend - that's when they told me that MAF seems to be the cause of low mileage) and watch the mileage for a few days...and along with that probably clean my MAF (there is lots of info on how to clean a MAF on the internet)...then monitor the vehicle for a few days and if the mileage continues to stay low...or I get the CEL (I haven't got the CEL yet with the current state of the MAF)...I should consider replacing the MAF.

The higher voltage reported on the MAF was only .05 V higher than the spec. by the way...cleaning the MAF might just fix it...

Any suggestions?

drummerboy

As I stated in my original post......We (My Brother), had lengthy discussions back and forth with some MB Rep.

Under 100K Kilometers......I should have made that clear, sorry!

It was considered a major component. and was covered under the major component warranty.

Just a note:
We drove the vehicle with a bad MAF for a long time........lack of power and hesitation.
Finally unplugged the MAF.....worked great!
Ran it like that till they finally fixed it!