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1994 s600 coupe
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685 Posts
Discussion Starter #1
I'm getting a strange code that makes no sense on my SnapOn MT2500 scanner,
code 15 TWC overheat control module N58 (Jap.) circuit
TWC is 3-way converter, and there are no converters on my car.
control module N58 circuit, what is that ?
Jap can only mean that code pertains to vehicles made for the Japanese market ?
any help appreciated, what is this ?
 

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1994 S600 Coupe, 1995 S600 Coupe
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2,002 Posts
What module was under test? LH?
Try making a simple blink code test light and check whatever module is giving the code and see what you get. The result you are getting may be the result of the non-Mercedes scanner you are using. Does it come back if you clear it?

I'll check later for what N58 is.

Jon
 

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1994 s600 coupe
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685 Posts
Discussion Starter #3
the code came up when scanning both the Diagnostic module, and the left side bank 2 LH module.
there is an N59 module, i.e. the Diagnostic module...but no N58
strange....but this is not the first time I pulled a code there was no explanation for.
I got another code that didn't match the chart as well but that has long disappeared.
if was for the EGAS module. well I changed the EGAS with a used Ebay module, and that other code went away.
the limited info found online said code 15 is linked to a misfire condition,
meaning raw gas in the exhaust. so it says "TWC overheat" cuz it's anticipating that result from a rich condition with cats still on the car....making me think perhaps I have injectors stuck open. that would do it.
stuck injectors will cause such an extremely rich condition it will throw it into open loop because it pegs the o2 sensor at a maximum high value, and the Lambda control no longer can compensate, the injector(s) are on constantly.
when I tested that side injectors by shutting them on/off with the scan tool, 2 of them didn't seem to respond as they should when I shut them off. as if they stayed partially on.
 

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1994 S600 Coupe, 1995 S600 Coupe
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N58/1 and N58/2 are Japan only cat overheat modules, according to WIS. They are part of a system, including sensors and a warning light for Japan only. As I recall Japan requires or required these because of grass and paper caused fires from cats. Why your car has this code is unknown. Maybe because you are using the early LH modules in a somewhat later car?

Startekinfo info says "not used" for code 15. However, that version of Startekinfo only includes US cars as noted several places. It also says that codes 4, 10, 11, 16, and 17 can be displayed on vehicles produced up to 7/91(!) even if no fault present. That brackets code 15, so maybe there was an issue there also??

Jon
 

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1994 s600 coupe
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685 Posts
Discussion Starter #5
yes, I saw that early 1991 codes can come up, on cars with no true problem, on StarTek.
I'm going to do an I.D. check using the scanner to see if these are USA modules, or Japan modules, or ??
that will tell me. stay tuned...hopefully it's a code I can just ignore.
 

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1994 s600 coupe
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685 Posts
Discussion Starter #6
found it- one connector wire was broken on the right side EGR switchover solenoid, bolted to intake, from when I was working on the EGR valves. resoldered it, cleared codes, both code 15 and 16 are gone.

checked the LH and ignition modules, all are USA 1991 versions.
both LH are 3/91
 

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1994 s600 coupe
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685 Posts
Discussion Starter #8
I think it's what you said, it throws one code and another one near it on the number list...
because it threw another code that didn't exist in the past too, I think it was code 48 ?
 
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