Mercedes-Benz Owners Installing Wiring Harnesses in Cars to Avoid Costly Engine Repairs
Owners of certain Mercedes-Benz models have begun installing wiring harnesses in their vehicles—not for an electrical issue, but an engine problem that can lead to costly repairs.
According to The Autopian, many automakers in the late 2000s began shrinking displacement and adding turbochargers to their engines, especially in Europe.
Mercedes-Benz swapped out its 5.5-liter naturally aspirated M273 V8 engine with the 4.7-liter twin-turbocharged M278 V8, beginning with the 2012 model year. While this provided a significant increase in torque and higher EPA fuel economy, problems have cropped up with the M278’s new style of camshaft position sensors.
The camshaft position sensors and cam magnets are inserted in holes in the engine, where they monitor camshaft position. One end of the sensor makes contact with the engine, while the other end plugs into a main wiring harness that connects back to the engine control unit.
The problem is, oil can often make its way through a worn out camshaft position sensor or magnet, reaching the wiring harness pigtail connected to the cam sensor. That engine oil will then make its way down the main wiring harness, reaching the ECU and leaving severe damage behind.
Several owners within the Benzworld forum claim to have experienced oil in the engine wiring harness, The Autopian noted, with one repair bill allegedly reaching $7,000, and another claiming they were billed $11,000 as a result of the problem.
However, a simple, low-cost safeguard has been proposed: installing two sets of cam sensor harness extensions to cover all the sensors and magnets within the vehicle. While it isn’t a solution that eliminates the problem, the logic is that it will prevent damage to the main engine harness, as opposed to cam sensors, magnets, and the wiring harness extensions, which would all be cheaper to have replaced.
