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Discussion Starter #1
Hey guys, i need some advice for some diagnostic codes I got off the LED next to the battery.

Here they are:

#2 O2 Sensor Inoperative (this has come up before but only since summer)
#5 Needs no explanation. Don't worry about this.
#6 Idle Speed Control Inoperative (Now this is weird. I've only received this when I jostled the throttle cable next to the intake manifold on the body. A quick tumble of the key and a CEL reset fixed this, but on top of that the ASR light came on.)
#12 Oxygen Sensor heater open or short circuit (this is new).

That said, there are no driveability issues whatsoever. She drives very nicely, still has all the power, can reach its top speed no problem (teeheeheee).

I reset all the codes and will see if they show up after a couple starts.

What advice can y'all give me for these codes? Car has 117.5k miles on it and counting.
 

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Hey guys, i need some advice for some diagnostic codes I got off the LED next to the battery.

Here they are:

#2 O2 Sensor Inoperative (this has come up before but only since summer)
#5 Needs no explanation. Don't worry about this.
#6 Idle Speed Control Inoperative (Now this is weird. I've only received this when I jostled the throttle cable next to the intake manifold on the body. A quick tumble of the key and a CEL reset fixed this, but on top of that the ASR light came on.)
#12 Oxygen Sensor heater open or short circuit (this is new).

That said, there are no driveability issues whatsoever. She drives very nicely, still has all the power, can reach its top speed no problem (teeheeheee).

I reset all the codes and will see if they show up after a couple starts.

What advice can y'all give me for these codes? Car has 117.5k miles on it and counting.
If you clean the MAF(mass air sensor) all the problems will clear. If it failed after cleaning then you may need to replace it. I heard it £245 from Bosch. Buy any cheap one from eBay may not solve your problem.

If you can afford a Merc, sure you can afford a Merc STAR(you are alright here with not a genuine one)

Happy motoring and have fun. :D
 

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Discussion Starter #3
If you clean the MAF(mass air sensor) all the problems will clear. If it failed after cleaning then you may need to replace it. I heard it £245 from Bosch. Buy any cheap one from eBay may not solve your problem.

If you can afford a Merc, sure you can afford a Merc STAR(you are alright here with not a genuine one)

Happy motoring and have fun. :D
How do I clean it?
 

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If you clean the MAF(mass air sensor) all the problems will clear. If it failed after cleaning then you may need to replace it. I heard it £245 from Bosch. Buy any cheap one from eBay may not solve your problem.

If you can afford a Merc, sure you can afford a Merc STAR(you are alright here with not a genuine one)

Happy motoring and have fun. :D
This has NOTHING to do with the MAF. It clearly states (2 & 12) it's to O2 sensor that's bad!!!!

On these models, the O2 sensor has an expected lifetime of 80,000 miles, so you are already way over the designed lifetime. :D

Get a universal Bosch O2, the special tool (about $8 from most shops) and replace the sensor. Add anti-seize to the threads of the new sensor before installing it.

Driving with a bad O2 sensor will affect your MPG, fuel mixture and could destroy the catalytic converter due to a bad fuel mixture.
 

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Chinny,

There are 3 major computer modules in your 1994 E320:

DM - Diagnostic module
HFM - Fuel injection / ignition control
EA - Electronic accelerator / cruise control / idle control


The LED light you are using now shows codes only from the DM. You also need to also pull codes from the other two modules, using a separate, hand-held LED blink code reader (or better yet, a digital scanner, if you can afford the ~$500 for a used Snap-On). Click here to download my diagnostic code reference guide for your car - this should help answer some questions for you. The DM codes are what trigger the Check Engine light, but they are often vague & generic faults. The detailed faults will appear in the HFM and EA codes.

A digital scanner will also show live data... yes, there is live data available from this "old" OBD-1 system, click here and see page 2 for a list of the live data parameters available.

:sawzall:
 

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On top of a bad O2 sensor...what else can arise from the bad sensor and anyway I can do a quick assessment with the potential issues without the tool? I can't afford that right now :D
It should be fairly easy to test your O2 sensor for function. The older zirconium dioxide sensors used in our cars only have 3 reference voltage values that the computer reads. 0.2 V = lean, 0.8 V = rich, 0.45 V = lambda. So if you have an RMS multimeter you can bridge the meter between the contacts on the O2 sensor and see if the values are correct for cold engine startup (rich), to warmed up engine (lambda).

Most likely, your O2 sensor is failing. They are sort of like glowplugs in that they heat up to 800 C in a very short period.
 

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On top of a bad O2 sensor...what else can arise from the bad sensor and anyway I can do a quick assessment with the potential issues without the tool? I can't afford that right now :D
Although you don't need a digital scanner, you can't do any assessment of potential issues without at least the LED impluse code reader. You can make one yourself with about $10 in parts from Radio Shack, or you can buy one from eBay fromthis seller for $36. Whatever code list he sends you, though, toss it - use the file I described in my previous post.

:surrender:
 

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I Always see the idle speed control code when ETA's are on their way out.

Jonathan
 
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