One problem related to wiring has been reported for the 2004 Mercedes Benz 230. The most recently reported issues are listed below.
Check engine light came on. Repair done to fix issue found as stated by mercedes park place tech in dallas TX - 'found engine control module sending incorrect signals due to oil damage. Also found air intake temp sensor with oil damage. Necessary to replace engine control module and intake temp sensor. Replaced engine wiring harness, camshaft position sensors and both O2 sensors. The total charge was $3432. 12. This was a known problem due to manufacture defect that had subsequent recall 2009100001. This recall was performed on my car on 7/25/2011. By this time I had already paid for the repair and therefore no issue was found or repair required. . I believe that I should be refunded for the this repair since it was a recall.