96 SL500. Last summer on a very hot day the check engine light came on, car still ran perfectly. MB dealer pulled an oxygen sensor code, they said not to worry, cleared it and I was on my way.

Last week, again on a very hot day, the check engine light came on, like last time the car continued to run perfectly. The MB dealer once again pulled a code for the oxygen sensor and said there was an old code stored for the MAP sensor which could be related. Anyway they went ahead and replaced the oxygen sensor but could not get the car to pass their diagnostic tests. They traced it to the fuel injection control unit, they listed it as the ME Control Unit on the invoice. Anyway this part alone costs $2300!! I guess it is a sealed unit and has to be completely replaced. They put my old O2 sensor in and I left it at that for now.

They were able to clear the engine light and told me to continue to drive it normally, but to expect the check engine light to go on. They said I would probably not damage anything, but to bring it back if I had any hard starting or rough idling.

Anyone have any insight to this? It is a rather expensive repair I would like to avoid if I could, but I hate to see the check engine light on all the time and worry I could damage the car somehow if it runs too rich/lean. Any advice would be appreciated.

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2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

Drive it and keep your eyes on ebay. I see them pop up there. I found one on ebay 100.00 for my V-12 that I'm sending to Renntech. You may want to make sure your wiring is intact as that may trigger a CE light also. Sounds like you have faith in this dealer though, so their diagnosis is probably correct.


good luck


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CR

If your rear view mirror has the red and green lights on it I do not belive you can use an ME unit from another vehicle as it is married to the VIN.

I would encourage more tests regarding the O2 sensor circuit. It is possible that the ME is at fault; however, with the read codes, monitor actual values for a short time, replace a component then clear codes approach something may have been overlooked. You have every right to request what tests were performed in order to lead them to a conclusion that the ECU is the problem.

A 2300.00 oops that wasn't it now what situation is uncomfortable to both parties!

They actually had a new O2 sensor installed and said the car failed diagnostic testing with the new O2 sensor, but how exactly they traced it to the ME unit I do not know. I am bringing it to an indie for a second opinion next time the engine light comes on.

And yes I do have the green and red lights on my rearview, so this means I HAVE TO get a ME control unit from MB?

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2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

You may want to check with an electronics repair company by the name of Beckmann Technolgy. If the unit is indeed faulty they may be able to help, you will need to check with them to be certain.

http://www.beckmanntechnologies.com/products.html

You would be better to keep the name handy and use it when you deal with your independent. Beckmann puts a pretty high list price on retail sales. There is a good lick for your independent so let him use it to give you a good deal if that is the problem.

The O2 sensors have a biasing voltage sent from the controller. if that is missing the controller is bad. I would suspect any other diagnosis without a second opinion.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Thanks guys, I am going to call up the dealer next week and see if they documented what they looked at specifically.

Does the fact that the engine light comes on with an O2 code only on VERY hot days mean anything? And could I be damaging anything running this way? The dealer said probably not.

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2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special