My 2003 C240 with 20k miles on it threw a code and the diagnosis is "to lean on right bank". What I'm wondering is, what is the cause of this? Is this a common problem? Also, I'm in San Antonio/Austin Texas area. Does anyone know of someone to do the repair other than the dealership? Any help is appreciated.

By the way, the car was fine till I took it in for A service last week. Now it runs rough when I come to a stop and the car goes to idle. The tech that did the A service said "the battery did not pass a battery test" What the heck does that mean?

Thanks!

 

Hi,

The tech that did the A service said "the battery did not pass a battery test" What the heck does that mean?
Bottom line is you need a new battery.
The battery is tested by putting a load (resistance) across it and observing Current/Voltage. This test makes the battery work hard (like starting on a cold morning) and it indicates IMPENDING battery problems although all may appear OK at present. The alternative is to wait till the battery actually lets you down at the worst possible moment. Batteries usually last 3 to 4 years.

Lean on Bank 1.
For some reason the Engine Fuel Management System EMS has been unable to set the correct mixture on Bank 1. It has basically run out of adjustment which is normally undertaken hundreds of times a second in order to ensure that the mixture is correct and that emmissions are within legal limits. Since it is only on one bank it is likely the oxygen sensor which is used to determine how much unburnt oxygen there is in the exhaust gas that is faulty. A relationship exists between O2 content and ideal mixture strength. The problem could be an injector but this would likely give a misfire. It is unlikely all 3 injectors on one bank have gone bad at once. the fuel pump supplies all six injectors from the same supply.

The scanner used to determine the Weal Mixture can also examine wether the O2 sensor is working correctly by examining the data coming from the sensor. If it is the sensor this is an easy DIY task if you have the correct tools. Not sure how expensive the sensor is. Pure guess 200USD?

Stuart

 

Well, come to find out they didn't button up the air filter assembly correctly. Once it was closed properly...no problem!

Thanks for your help and I'll replace the battery. Is it a standard car battery or is there something special about a Mercedes battery? Can I do what I've always done and pick one up at Wal Mart for replacement?