Here are the issue I have

Original Owner ML320 1998 with 163000 miles on it. Serviced every 10k with Sythetic Oil from beginning. It was one of the first.
with Pages and Pages of Factory recalls.

I had the problem of engine not shifting in long trips with hot weather during long highway driving. (Like some others past posting)

http://www.peachparts.com/shopforum/printthread.php?threadid=69113

http://www.peachparts.com/shopforum/showthread.php?threadid=84290

http://www.peachparts.com/shopforum/showthread.php?threadid=86170

It has been a while that I have not run to that problem. I didnot change anything. Dealer could not find a flaw.

I also ran into problem of low oil light on long trips.
I checked oil with the dipstick. Sometimes it shows low sometime is normal.
Puzzeled by that one??
http://www.peachparts.com/shopforum/showthread.php?threadid=59370

So far I have not run to that problem. I didnot change anything.

Recentely My engine light came on and off.

The mechanic told me today I need to change the Mass Air Sensor.
If I don't change it. It gone ruin my catalytic Converter.
Is that true?

What does these code stand for P0173 and PO170?

How do you know your MAS need to be changed?

So far on the ML. I just do the A service at the dealer(every 10k service).
I don't do the B service anymore. (B service they donot do anything it seems except air filter for AC).

So far I have not change anything major(i.e Spark plugs, Fuel Pump, Transmission oil, and Coolant and etc....) The dealer has never mention you need to change it.

How do you know when to change Spark plugs and coolant?

The only major changes were the belt, oil pan, o2 sensor, gas sensor.

Do you recommend to change anything proactivley? or
Should I drive it until it failed? Then change the MAS, Fuel Pump, and etc.......


Thanks in advance,

I can't see it ruining the catalysts, but you definately need a new mass air sensor. Also I like to change the intake duct seals (there are 2 of them) and the air filter whenever I do an air mass.
They are an extremely common issue, and I am very surprised you made it this far without one before.

There are maintenance schedules in the owners manual. Spark plugs are 100K limit. Coolant every 3 years. Sounds like several things need to be taken care of!

There are a bunch of things that need maintenance as mentioned elsewhere on this forum.
Lets see if my memory is still working......

Brake fluid every 2 years
radiator coolant every 3 years
spark plugs every 4 years or 100K
engine air filter every 4 years
cabin filter every so often, I do it once a year (dont' know official time for this)

Seems like the MAss Air Filter is a very easy change and very common wear item for all Benz's. Not cheap though...