you can buy a code reader for $50 on ebay.
I bought mine at sears for $79.

I do not know if it will tell you what your problem is.

My last codes were just mis fires. but reading the forums pointed to MAS or vacuum leak.
I still have a rough idle. its been 2 months now i cant figure it all out.

in terms of easy to fix. search these forums for instrustions and most everything is easy to fix if you have courage and good light.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

You can get the Bosch (same as the MB, without the MB logo) part for considerably less money. I purchased mine from a supplier in San Diego for about US$200.

__________________
1973 280SE 4.5 (Sold)
1984 LWB 280GE (Sold)
2000 G500 NMLE - "Deep Throat"
2007 ML320 CDI (Sold)
2010 Porsche Cayenne S Transsyberia TipTronic (Sold)
2010 Audi Q7 3.0 TDI (Sold and Sorely Missed)
2014 ML350 BTC
2015 Audi Q7 3.0 TDI (On Order)

I had no idea these were so cheap - I thought to get good information the software necessary was at least several hundered dollars??? I've seen ads for this. I'm certainly willing to give it a try for the price you say it can be had.

Thanks!

__________________
Francis E. Abate
Automotive Restoration & Preservation
Sheet metal, trim and upholstery

The inexpensive ones will get the generic OBDII codes, but cannot get the MB proprietary codes. Getting those proprietary codes requires a checker that costs $2,000-3,000 or more.

However, those generic OBDII codes can tell you a lot; so one of those inexpensive readers can be well worth the investment.

__________________
1973 280SE 4.5 (Sold)
1984 LWB 280GE (Sold)
2000 G500 NMLE - "Deep Throat"
2007 ML320 CDI (Sold)
2010 Porsche Cayenne S Transsyberia TipTronic (Sold)
2010 Audi Q7 3.0 TDI (Sold and Sorely Missed)
2014 ML350 BTC
2015 Audi Q7 3.0 TDI (On Order)

The $50-$79 code readers will do what AutoZone does for you for free.
After having them read my codes twice, and clear the codes...I decided I should buy my own.

Looking at Ebay this morning, looks like they are down to $35 delivered.

__________________
Steve Danville
what i did myself.
CPS
rear shocks
MAS x 3.
SparkPlugs (twice)
Fuel pump & Filter
Window switch
replaced both failed horns with Honda horns.
Cleaned ERG Tube
Oil changes
Oil consumption Fix
Brake Pads
A/C Recharge
Anti-Freeze change X 2.
Front Shocks. Monroe. $90
Mercedes Warrenty Work:
Harmonic balancer,power steering clamp. Cat converters.Drive Shaft Bearing.s
Replaced Outer Lower Tie Rods and front lower ball joints at 156,000 miles

Good deal, thanks guys - I will check it out. Didn't know Auto Zone would do this for free either!

__________________
Francis E. Abate
Automotive Restoration & Preservation
Sheet metal, trim and upholstery