Car Problem Reports

Mercedes-Benz E320 Insulation Degrades on Engine Wiring Harness and Leaves Conductors Exposed

Mercedes-Benz E320 Problem
13 Reports
Me Too

Model Years Affected: 1994, 1995

Average Mileage: 105,980 mi (23,800 mi - 200,000 mi)


The engine wiring can degrade because the insulating material falls off leaving the bare wire exposed. This can cause many problems depending on which wires are exposed and what they touch.

  • Visitor, , 114,000 mi

    most of the wiring harnesses are exposed, and most of the sensors have poor connections due to lack of insulated wires. they are cracked and extremely poor. occasionally when i enter certain turns usually sharp right freeway on ramps i believed caused the wires to touch causing my vehicle to lose power and almost cut out, but it recovers on its own and proceeds onto the freeway but in heavy traffic areas almost caused other cars to rear end me and or have to swerve to avoid me, which is dangerous. there is usually no warning from the car, it just happens out of no where when least expected. weather/temperature may also contribute to this matter, but could happen any time and usually on the same highways and or turns, on ramps ect.

    i read that mercedes used biodegradable coating on all their wiring without takin into consideration the climate changes and the heat radiated from the engine. some of the wires i have recoated with electrical wire but some wires are difficult to reach making it difficult to insure the wires do not touch.. Some day i plan to purchase new ones but i am unemployed which makes repairs difficult to keep up. as for now the car is not working and parked in the driveway.

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  • Visitor, , 90,000 mi

    Engine harness wiring insulation failure

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  • Visitor, , 200,000 mi

    The biodegradable insulation that Mercedes chose to use does actually degrade by design. Unfortunately, I'm not done using the car yet. There are areas around the headlamps and side marker lights that the wire insulation does literally crumble off into your hands.

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  • Visitor, , 89,000 mi

    Car surges to high ram immediately on start up.
    Replaced the wiring harness to the mass air flow sensor and the fuel injectors.

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  • Visitor, , 110,000 mi

    Cracked wire harness insulation was starting to cause problems with engine diagnostics.
    The problem started at 80K miles, I had Mercedes replace a single wire at the time and complained.
    They blamed me for having the car overheat and did not tell me the factory used the wrong insulator on the harness. Shame, the car never overheated.

    I eventually had it replaced at my Mercedes mechanic for ~$1200 at 110K miles.

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  • Visitor, , 102,000 mi

    Biodegradable insulation visibly cracking and falling apart where wires were visible at plugs attaching to sensor on thermostat housing at the front of the engine. Found a 2007 with the non-biodegradable insulation at a junkyard and replaced the original, starting with the big computer plug behind the battery and just worked around to the front of the engine replacing each connection with the new harness equivalent one at a time. Under three hours.

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  • Visitor, , 113,000 mi

    To replace the wiring harness, it took me about 2 1/2 hrs. Some of the connectors are hard to access and you have to move a couple of component parts to get too them.
    If you are not auato repair savvy, have it done.

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  • Visitor, , 113,000 mi

    Insulation on eng. wiring harness cracked causing no ignition voltage and shorts. If not rpaired, in can cause ECM failure.
    Fix. Replace entire eng. wiring harness, $700.00

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  • Visitor, , 105,000 mi

    I paid $i,800. for my mercedez e-320.Only to find out a wiring harness problem with the insulation on the wire.
    My question is why isn't there a recall on this problem?
    Dos'nt make any sense to me why Mercedes benz dosen't stand up to the plate and replace this safety hazard.
    To replace the part is rediculouse in price and labor.
    If you can find the part for resonable price i will be glad to pay you for it...

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  •  Rookie

    The engine wiring harness on my 1995 E320 Cabriolet (124 chassis)shorted. I've already replaced the high voltage pro-tection relay. I've ordered a new OEM harness ($945). How many hours should it take to remove the old harness and install the new one??? What can you tell me about TJ's Bobby and Steve's Auto World in Bryn Mawr, MN?? How about Huber's Imported Auto Repair??

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