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Super mechanic
Super mechanic, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 16816
Experience:  ASE Master, 30+ years exp. troubleshooting, diag. electrical, collision
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I have a 1997 mercedes benz E320. The engine electronics light

Resolved Question:

I have a 1997 mercedes benz E320. The engine electronics light along with the check engine light came on. The DTC READ PO 300, 302, and 304. I know that these codes indicate cylinder 4, 2, is misfiring and 300 indicate random cylinder misfire. I was told that this is probably due to a defective fuel pressure regulator and I have purchased one. My question is two fold, first, do you agree with this diagnostic, and second how do you replace the regulator. P.S. The vehicle is running and idlling rough and I believe I have located the part on the vehicle but just in case please describe its location for me
Submitted: 8 years ago.
Category: Mercedes
Expert:  Super mechanic replied 8 years ago.

Hello and welcome to Just, Super mechanic here. About your vehicle.


That may be your problem. It would be easy enough to replace. If you don't know what the fuel pressure is at, you might want to take off the vacuum hose at the fuel pressure regulator and see if there is any raw fuel in it. That would be an indication that it's bad.


Here are the instructions on it along with a picture of where it is.




Component Identification, Shown on engine 104






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