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W124-94 E320
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29 Posts
Discussion Starter #1 (Edited)
hi all,
the check engine light is on and I want to know how to check the box which is next to battery.
and if any advice that will be great, the car runs okay and start fine but still has check engine on:confused:
also i wanna know if I pressed the check button in this box while the car is running, is that okay?
thanks
 

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95 E320 Cabriolet, 140K
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1,332 Posts
This link has a lot of information you need and provides links for a lot more information.

E320 16 PIN DTC Charts inc. pin 8, pin 14 - ShopForum

Code reading is done with the engine off, ignition key in the on position.
You'll not only want to read the built-in diagnostic module codes, but also the sub-codes, which can help with further diagnostics.
 

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W124-94 E320
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29 Posts
Discussion Starter #3
Hello Guys,
after I did a check for the check engine light, The Code reading flashed 12 times.
According to this link (E320 16 PIN DTC Charts inc. pin 8, pin 14 - ShopForum)
12 Heated oxygen sensor heater circuit open or circuit short
So what could it be??
Is it mean the O2 sensor or it mean something else?, Since in the same link I mentioned above it says (2 Heated oxygen sensor faulty).
any advice?
Thanks for all
 

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About a dozen 1988, 1989, 1990, and 1991 sedans, wagons, 4Matics and 1 coupe
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5,466 Posts
Starting in the early 1990s the O2 sensor on a lot of vehicles contained a heating element. This accelerated sensor warm up time so it could provide accurate data to the fuel injection computer sooner.
It sounds like the heating element in your car's sensor has failed. It's also possibly, but unlikely, that the heater circuit connector is unplugged or the wiring is damaged.
As you mention, the car will drive normally because the sensor does warm up anyway within a few minutes. Replacing the sensor will, however, get the system working properly again and reduce HC emissions during cold engine starts. Something we should all be thinking about...
Plus the annoying check engine lamp will turn off.
 

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93 190E 2.3, 94 E320 (sold), 01 E320, 99 S320, 18 Durango
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4,978 Posts
His CEL appeared just after replacing a broken AC High/Low switch with a used one from a 1992 300E and put on in his 1994 E320, could this give a CEL?
 

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W124-94 E320
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29 Posts
Discussion Starter #7 (Edited)
okay guys let me mention something I forgot to tell; in the same day the check engine light came on my mechanic was doing some fix on my AC and he found a leak coming through the Pressure Switch at Receiver Drier, and he replace it with an used one he bring it from one of the car parking in his shop which was 300E, So any of you guys think that this switch could give me a check engine light or it happened by luck
Note: the car start and run very nice as usual, I see no difference
thanks
 

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06 S500 / 03 Expedition / 92 Wrangler
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164 Posts
oxygen sensor / CE light

Hello - not to be a hijacker but this is related / might help. I have had the CE light on so I bought a new universal oxygen sensor off of ebay - supposedly a Bosch unit but it was cheap. It was a pain to install due to the short lead wires. There are 2 white, one black, and one gray.

Does is matter which wire the white goes to? Are the two whites interchangeable. The reason I ask is that the CE light came back on after resetting it. I just got back from radio shack and bought the LED and switch so I will check the code but I wonder if the white wires are the same.

tnks all!
 

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06 S500 / 03 Expedition / 92 Wrangler
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164 Posts
code check still shows o2 sensor

Anyone know if it matters which white wire goes to harness on universal O2 sensor? Don't want to switch them and blow something out...
 

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06 S500 / 03 Expedition / 92 Wrangler
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164 Posts
code check still shows o2 sensor

Anyone know if it matters which white wire goes to harness on universal O2 sensor? Don't want to switch them and blow something out...
 
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