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99 CLK 320
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Discussion Starter #1
The "E" has been running rough lately.
Home Brew Code Reader says code 9 and 22 from pin 8
Decoder sheet says oxygen sensor is out of limits (code 9) and iginition/coil for cyl 2&5 (code 22)

Priced the O2 sensor at about $85 plus/plus. Crawled under and found the sensor in the tail pipe and connectors inside the passenger footwell carpet area.
I guess "IF" I can get the sensor out of the tail pipe(looks a bit of an unfavorable angle) it just snakes through the grommet. Big "IF" there.

As for the cyl 2/5. I was told it had new "heli coils" put in around 50K miles ago.
Surely they last longer than this. Haven't pulled the plugs yet for inspection.

I guess I'm just irritated that if I put in a new O2 sensor and there's still an ignition problem with 2/5, I'm out $85 plus aggravation. On the other hand if I put in new coil/plugs on 2/5 and still have the O2 sensor problem, I'm farked again.

What do you Benzworld guys/girls think I should do first:
--Coil/plugs first or
--O2 sensor first
--Just do both and chalk it up to experience
 

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A helicoil - Heli-Coil | HeliCoil Inserts | Helicoils Screw Thread Inserts | Emhart Teknologies - is very different than an ignition coil. It's very possible you have two problems and will have to deal with both of them. The ignition coils over cylinders two, four and six are interchangeable and can be moved around, and the fault code should follow the bad coil. Are you getting the O2 sensor code on pin 3? My next step would be to erase all codes and see what comes back.
 

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Discussion Starter #3 (Edited)
A helicoil - Heli-Coil | HeliCoil Inserts | Helicoils Screw Thread Inserts | Emhart Teknologies - is very different than an ignition coil. It's very possible you have two problems and will have to deal with both of them. The ignition coils over cylinders two, four and six are interchangeable and can be moved around, and the fault code should follow the bad coil. Are you getting the O2 sensor code on pin 3? My next step would be to erase all codes and see what comes back.
That would explain things a bit. Maybe I do have a bad coil AND O2 sensor
The E had a valve job along a bunch of other things at 180K miles.
I just put 2 and 2 together and came up with 22. LOL.

I'll do as you suggest and swap coils around. Do you think if I swapped out the coil/replaced all three coils, the O2 sensor reading would normalize and go away?

Didn't get any codes on Pin 3. Cleared codes, but got repeats on Pin 8. Also got code 2 on pin 14 (stop lamp switch, cruise control, etc) Cruise control works -- checked it today on a grocery run.

Thanks again for all your help with the codes/reader
 

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Moving the coils around will just serve to show that you have a bad one and which one. I would start there since a misfire could be causing other issues. $63 at AutohausAZ.com - not too expensive.
 

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Discussion Starter #5
Moving the coils around will just serve to show that you have a bad one and which one. I would start there since a misfire could be causing other issues. $63 at AutohausAZ.com - not too expensive.
OK, so I swapped out coils 1 and 2. While I had the cover off, I pulled all the plugs for inspection.
--Plug #1 had some serious oil on the threads. What's up with that?Normal carbon on the tip.
--Plugs #2,3,4 and 6 all looked pretty good. Normal carbon. Nothing excessive.
--Plug #5 had a little oil on the threads and normal carbon on the tip.

I noticed that the coils were not secured to the head at all. Whoever did the last work there didn't use and screws to hold the coils in place.

Anyway, after the coil swap, I still got code 9 (Oxy sensor) and code 22 (coil 1 cylinder 2 and 5)

:crybaby2:
 

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Are you sure your codes were deleted before you swapped the coils? Coils aren't attached - just sit there, held down by the cover I guess. If you did delete the codes, and the same code came with the coils swapped it means you have a problem downstream from the coil, most likely the connector under the coil on cylinder 2. Replace all three of them (2, 4 and 6). They are cheap, around $6 each. Oil in the spark plug well likely means bad valve cover donut around that spark plug. A new valve cover gasket set comes with the perimeter gasket as well as six rubber donuts for around the spark plug wells, also cheap.
 

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Discussion Starter #7
Are you sure your codes were deleted before you swapped the coils? Coils aren't attached - just sit there, held down by the cover I guess. If you did delete the codes, and the same code came with the coils swapped it means you have a problem downstream from the coil, most likely the connector under the coil on cylinder 2. Replace all three of them (2, 4 and 6). They are cheap, around $6 each. Oil in the spark plug well likely means bad valve cover donut around that spark plug. A new valve cover gasket set comes with the perimeter gasket as well as six rubber donuts for around the spark plug wells, also cheap.
Deanyel,

Thanks for your following my saga. Today I hit the "E" with parts--plugs, wires, boots, and coils. I also sprayed some CRC Mass Air Flow cleaner on the air temp sensor that attaches to the cross-over tube on the intake manifold side. There was some nasty looking stuff on those little wires. Anyway the "E" runs smooth now...real smooth.

I'll save the valve cover gasket/plug well gaskets for another day. It started to rain just as I was buttoning up the wire/coil/plug area. I didn't get a chance to clear codes before the sky fell.

Thanks Deanyel and all my Mercedes Benz brothers from another mother.

:thumbsup:
 
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