PeachParts Mercedes-Benz Forum - View Single Post

Steve M · #5 09-07-2011, 01:24 PM

First the Background: After reviewing my files, I realized that this car had thrown a CEL 4 years and 30,000 miles ago, due to a P0304, cylinder 4 misfire. The indy who worked on it replaced the plugs and the wires ("OEM Beru Wire Set $164.00") at that time. He expressed questions and concerns about the wiring harness. But like I said before, it's worked fine since then-in fact, if I had just not done the scheduled plug replacement, I would probably be fine. This all makes me think that I did not carelessly break something when I changed the plugs, but rather just disturbed something that wasn't able to handle it.

Also, I tried plugging my handheld scanner into the OBDII connection, and it doesn't want to work. I don't think I'd ever personally checked codes on this car, but others have.

Now for the plan: I went to the dealers to get my three parts today. First I asked him to double check the price on the harness. Now he tells me it is $1,840 - part # 202 440 18 05. I am obviously more determined than before to avoid this expenditure.

The main part that I ordered yesterday was the plug, part# 202 540 60 81, which cost $16.00. It was actually substituted with 026 545 90 28. Interestingly, it is the exact plug as I have, but it has a really nice 2 meter long pigtail on it! So there is no need for the two bushings, which go in the plug. It is apparent to me that I can use this assembly to bypass the wiring harness completely (avoiding some difficult close quarters work on fragile wiring by the coil) and going directly to, .....uh, ...uhm, the ECU?

I have some homework to do. I will get the wiring diagrams in front of me, but I expect that I will have to get this pigtail attached to the engine side plug that attaches the wiring harness to the ECU. This may be difficult.

As always, thanks in advance for any thoughts on this approach.