SLK OBDII port

wiltsandy

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Driving home tonight the Engine Management Light came on but there was no discernible difference in the way the car behaved.

Can somebody please tell me where the OBDII port on the R170 SLK is so that I can hopefully pull of the code with my OBDII tester without having to resort to taking the car to the dealer next week.

Also, would anyone like to hazard a guess as to what the problem might be so that I've got an idea of where to start looking? I have fitted the starter line to the cam sensor so am hoping its not the ECU!
 

racall

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There is a port under the dashboard near the bonnet release gas pedal area.Well thats where they plug the star machine into.
I had my faults cleared yesterday.
 

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My engine management lamp was triggered by the o2 sensor before CAT. This was caused by overfuel due to throttle housing and butterfly oil contamination. Cleaned housing and butterfly, now ok.
 
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wiltsandy

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Thanks guys,

Found the port and I've got code P0131 which according to the diagnostic tool instructions is "O2 Sensor Circuit Low Volts (Bank 1 Sensor 1)".

Now to check all the connections and see if there's any oil contamination anywhere.
 

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Pull the camshaft adjust plug off and see if it is oily
 
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wiltsandy

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An update for anyone who may suffer the same problem.

Pulled the plug off the pre-cat O2 sensor and it was full of oil so I guess that's the cause of the low voltage. Washed it all out, put it back together and cleared the fault code so we'll see what happens now.

Also checked the connectors on the ECU and they're oily too :(. Removed the ECU and cleaned that up as best I could and I just hope that I've caught it time and that the starter line that I fitted last week to the cam sensor stops any more oil being pushed up through the loom.

Also checked the air filter/intake tubes and the MAF and they're clean with no oily residue so at hopefully that side of things is ok.

Fingers crossed now that the ECU will be ok and the O2 sensor will settle back to normal.
 
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wiltsandy

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Its a short time fix,

The only correct way to fix the fault now is to replace the wiring harness!!

How big a job is that and do you know how much a loom would cost?

I've been out for a drive and then re-checked and cleaned all the connectors again in the hope that with no pressure behind it now that the starter line is fitted, the oil will stop collecting at them. It does seem to be getting better so fingers crossed.
 

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Hi Andy

I had the same problem on my 230clk 2001 for months and months. Had the cam sensor wiring upgrade done and the problem went for a short while then came back. MB wanted to change every conceivable part in the chain at my cost. I did not do that and am happy to say that the problem went away, came back, went away etc for months and has been fine for 4 weeks solid now touch wood!!!! All I can say is maybe the oil does eventually burn off? Hope you get it sorted.

Regards

Andrew
 
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wiltsandy

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Thanks Andrew,

Working on the theory that the oil should have stopped moving through the loom now, I'm going to keep cleaning the connectors every couple of days as its not a big job. Hopefully this will prevent any future issues.

At least I have access to an OBDII tool to reset the O2 sensor code without having to resort to visits to the local dealer!
 

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Thanks Andrew,

Working on the theory that the oil should have stopped moving through the loom now, I'm going to keep cleaning the connectors every couple of days as its not a big job. Hopefully this will prevent any future issues.

At least I have access to an OBDII tool to reset the O2 sensor code without having to resort to visits to the local dealer!

I think too, that the oil must stop, you are doing the right thing by cleaning the connectors and keeping an eye on it
 
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wiltsandy

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It may be fixed!

Just thought I'd post an update to this oil issue for anyone that may be interested.

Checked the O2 sensor connector and the 4 on the ECU tonight after a 50 mile trip today and they're all dry of oil!:D The ECU light has stayed off too.

I hope I'm not speaking too soon but I think that I've caught it in time and with the starter line fitted no more oil will eek it's way out.

I suppose that I should now start looking at all the other connectors on that loom and to clean them up too. Does anyone have a diagram that shows where they all are?
 

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You have covered the main ones, so thats OK when oil gets onto the O2 sensor, it can put a film on it and this can tell the ECU to weaken the mixture, if it takes it too far then the lamp will come on, as long as the car drives fine, then do not worry about it
 
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wiltsandy

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You have covered the main ones, so thats OK when oil gets onto the O2 sensor, it can put a film on it and this can tell the ECU to weaken the mixture, if it takes it too far then the lamp will come on, as long as the car drives fine, then do not worry about it

Ok, thanks Malcolm. It's driving fine so hopefully it'll be ok. I'll still keep an eye on it over the next week or so though as it's an easy job to check the connectors.
 

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It might go on for another few thousand miles but the light will come on, once the oil is in the loom, is travels, it cant be explained why but it does!!
 

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Hi guys, this is a great site and have learnt loads in recent weeks. My son bought a 2003 SLK200K from miles away and then the problems started! I have just bought a cam adjuster magnet and starter-line to, hopefully, stop the oil leaking into the engine harness (engine management light on) Mercedes Swansea quoted £210+vat for the harness. I am hoping the wiring harness will clear itself eventually, as TV suggests, and I can now wash the ECU & air mass thingy out until it does! Anyway fingers crossed and thanks to all who help others here. Owen.
 

owenrich

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Hi Wiltsandy, I have a similar problem. Swansea Mercedes charge £210 + vat for a engine wiring harness. I put a message to your "chat" on the ignition section. Best wishes. Owen.
 
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wiltsandy

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This thread could run and run!

Thanks Owen for the price - at least I now know how much one is should I need it.

The car threw another ECU light again today with code P0131 (O2 sensor low voltage) but this time with P0130 pending also. I cleared the codes and checked the connector and it was dry.

Went for a short drive and on came the light again but this time for code P0130 only which is the O2 sensor circuit malfunction.

Am I correct in assuming that because oil was in the O2 sensor connector, its probably got into the sensor itself and wrecked it? If so it looks like a new sensor is going to be needed.

Also, is it only the pre-cat O2 sensor that is affected by oil in the loom. I haven't had chance to get under the car to check the rearmost sensor yet.
 

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Its not always the oil in the loom that does this.

When oil gets in the MAF, it is burnt in the engine, the O2 sensor picks this up and tries to adjust the engine by weakening the mixture in this case, it does not know that oil is on the O2 sensor, and it could just go away as it did when we had the fuel contamination troubles a year or so back.

If the car drives OK I would do nothing, and wait to see if the sensor burns itself clean, under these conditions it will weaken the mixture slightly and nothing else
 

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Today I fitted a new cam adjuster magnet & plug. Also a "starter line", cleaned out the engine computor unit (ECU) & as many plugs from the wiring harness as I could find. Not sure what is best to use in cleaning these, any suggestions please? Thanks to all you guys that have asked & answered questions on this problem, it has really helped. Cheers. Owen.
 


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