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Discussion Starter · #1 ·
My CEL is staying on my 99. It came on right after I was fooling around with the stock airbox and filter. I unplugged the MAF and the heat-exchanger plenum thing in the back of the box. I unplugged them w/o pulling the battery cables. After I put it all back together I went to drive the thing and the idle was really rough and the CEL was on. I followed the stickys about resetting the computer and doing the throttle body adaptation but it didn't make any difference. The light is still on. Does anyone in or near OC have a vag-com so we can pull the codes and reset this damn thing? Where can I get a vag-com and how much do they normally run? Thanks.

-Mike
 

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What you do to the airbox? I would just drive it and see if the CEL goes away. No need unplugging battery, that does not trigger CEL.

Did you put the hoses back on the airbox and tightened them? Don't ask how I know of rough idling and no power after fooling with airbox. :wink:
 

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Discussion Starter · #4 ·
Thanks for the reply. I have been driving it for about 2 weeks now and the light is still on. I need to get this thing figured out. All I did was unplug the sensors going to the top of the airbox so I could just pull the box off to get to the filter. I figured maybe I should have disconnected the battery before fooling with all the sensors. Oh well.

-Mike
 

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Have you checked to be sure the connector on the MAF sensor is fully seated. Perhaps you didn't get it on all the way.

I'd also do a diagnostic on the ICM and see if it coincidentally bit the dust as you were working on the air box. I doubt you'd be able to drive the car this long though if the ICM went bad.

BTW... I have disconnected both the ICM and MAF with battery cables in place without any problems.
 

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Discussion Starter · #7 ·
I noticed there was a white substance between the icm and the part in the box. Does that substance need to be ther to ensure better continuity? Or is it better for bare metal to metal contact. Would going to a Kragen or Auto Zone and renting the scanner tool be good enough? Thanks for the input. Can you do a diagnostic on the ICM w/o a scanner?

-Mike
 

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99 B5 1.8T said:
I noticed there was a white substance between the icm and the part in the box. Does that substance need to be ther to ensure better continuity? Or is it better for bare metal to metal contact. Would going to a Kragen or Auto Zone and renting the scanner tool be good enough? Thanks for the input. Can you do a diagnostic on the ICM w/o a scanner?

-Mike
Mike,
The white substance under the ICM is a thermally conductive grease. It provides improved heat transfer between the ICM and the heat sink in the air box. It needs to be there. If you removed it you should replace it with something similar. Most electronics supply places (probably even Radio Shack) sell compounds for this purpose. If you can't find anything, search the web for "Arctic Silver."

You can check the ICM with an standard ohm meter. I think there is a procedure in the Information Forum.

Here is the link... http://www.clubb5.com/forums/viewtopic.php?t=66779

Good luck.
 

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Discussion Starter · #10 ·
I think it's gonna be the ICM. When I disconnecte it I noticed there wasn't grease on the whole thing and only in certain spots. So I wipoed it off and didn't think about it. After reading the other thread on the ICM, it says not having grease can cause premature failure. So I am guessing that may be what has happened. Also the parts about it idling rough and the CEL staying is what has me thinking. I will test it with an ohm meter later on today and see what I come up with. If it turns out to be the ICM and I get a new one to replace it, should the CEL go off if that was all? Or do I need to get a scanner and delete the codes? Thanks.

-Mike

Forgot to ask, if I need to use an OBDII scanner: where is the plug for it?
 

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If you decide to replace the ICM check out... www.busdepot.com Many threads have reported that they have the best price right now on the Huco brand ICM. Supposedly it comes with a tube of heat transfer compound as well.

After you change it the CEL may remain on for a while - I am not sure - I believe it will take a certain number of starts without the fault present before it clears itself. The engine performance should return to normal immediately.

The OBDII port is located under the dash to the left of the steering column - just above where the driver's left knee would be.

Good luck.
 

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I am not sure if Arctic Silver is the right compound. Doesn't Arctic Silver hardens? I believe that you need lithium grease for the ICM.

Second the notion of BusDepot. They are cheapest.

Is your idle that rough? If the ICM is faulty then your car runs only on 3 cylinders, but that would be really rough.
 

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Discussion Starter · #14 ·
Thank you. I tested the ICM with an ohm meter and it tested fine. I put some dilectric grease under the ICM. Upon closer look one of the vacuum hoses was torn. I cut out that bad part and replaced it with a new hose and the y-fitting and after running it a while the CEL went off. The car runs a whole lot better: no more rough idle and it seems to have more pickup. I assume the loss of vacuum affected the turbo spooling. Thanks agin to all of you. :bow:

-Mike
 
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