How to test slk350 ecu - S-Class Mercedes-Benz Cars & Trucks

There is an issue with one bank of pistons, 4, 5 & 6.
Probably an injector issue.
Always fit OEM parts.

Does your CEL not come on at all on initial start? What about with the key turned to "on" & engine off?

Your CEL comes on as part of the vehicle computer's self test. During that self test, the ECU grounds the lamp to illuminate the bulb and after the test is complete, ground is removed and the light turns off.

When that light doesn't come on at initial startup, there could be a problem with the lamp's circuit leading to/from the ECU or the driver in the ECU that grounds it is defective. The CEL pin in the ECU should be tested for continuity and grounded externally (such as with a test light) to make sure it illuminates. IF it does light up, there's an issue with the ECU.

Do some research and find out what fires the injectors. Usually it will be the crank sensor. Find out if the ECU is getting its signal. If not I would think it is somewhere between either the sensor and the ECU. If it is, check between the ECU and the injectors. If everything tests good, you might need an ECU.

And I mean if the crank sensor is sending out a signal, and the connector to the ECU is receiving the signal, and the harness between the ECU and the injector rail are testing to have good continuity. Don't just run out and buy a new or reman ECU without making sure you need one.

https://www.manualslib.com/manual/557086/Mercedes-Benz-Slk350.html?page=292 or

http://mb-teilekatalog.info/?lang=E&mode=BM&class=1&aggtyp=&markt=AG&mmod=350
and choose option

Installing J&R ECU - YouTube

? 2:29
www.youtube.com/watch?v=mRyDo0-JBQ0
Mar 19, 2012 - Uploaded by Aaron Wise
Installing J&R ECU on 2007 Acura TL-S. ... 2013 Acura TL SH-AWD Review, Walkaround, Exhaust, Test Drive - Duration: 14:16. by Redline ...

Immobilizer bad? ECU bad? - AcuraZine Community

acurazine.com/forums/problems.../immobilizer-bad-ecu-bad-863716/

Jul 21, 2012 - It says to have the ecu reprogrammed and if that doesn't work then to .....Join Date: Oct 2007 .... If relay tests good move on, if not replace it. total cost under $20 .... Check Emissions CEL, hrothgar02, Second Generation RDX ... Scanner not detecting ECU
May 22, 2012
Dealership "Re-Programmed" 07 TL Type S computer??
Jun 22, 2011
Resetting ECU makes me happy :)
Oct 9, 2009
Resetting your ECU: After mods and Environment changes
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Check if it's a convetible

Possible motor mount failure.

It must be done with a scan tool

Yes you can.  The bulb number is a "D2S" if you have the HID (High Intensity Discharge) bulbs.  Most auto parts stores will need to order them but it should only take a day or two.  O'Reilly Auto Parts shows the bulb costing 89.99.  They are very expensive compared to the usual $10 bulbs on regular cars. 
If you don't have the HID bulbs, yours is a halogen bulb.  The bulb number is "H755".  This one is the $10 bulb.
Double check which bulb you need before purchasing one! Most parts stores can tell you which bulb you need just by looking at the car's headlights.