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Discussion Starter #1
OK.

2001 AC, 4WD. 89K miles

Lately the CE light has been coming on. It's been to the dealer twice and they can't find anything wrong. :confused:

* The O2 sensors are good.
* Timing Belt was replaced at 75K
* Fuel cap is tight
* Oil level is good.
* I buy fuel and different locations, so that should rule out a bad gas problem.

Other facts:

* The engine runs fine but I do hear a little valve chatter when I step on the gas to accelerate.
* The problem seems to happen more often when the weather temperature is in the 90's.

Any thoughts?
 

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Have you cleaned the MAF lately? I know this sounds rudimentary but how are all the basics?

  • MAF
  • Throttle Body
  • Air filter
  • Plugs and wires
  • Coil Packs
  • PCV
Is it shifting good? Transmission fluid clean? Have you done anything recently that might cause the engine to dump some carbon? I am wondering if you have a cat on the way out?

How does the oil look? Is it getting dirty faster or does it last the same mileage as before?

It would really simplify things if you were able to pull codes. The ECU should not only hold any codes but also all the operating parameters for an extended period of time. I am surprised the dealership was not able to pull codes or find anything.
 

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Premium Member
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13,116 Posts
Discussion Starter #4
Have you cleaned the MAF lately? I know this sounds rudimentary but how are all the basics?

  • MAF
  • Throttle Body
  • Air filter
  • Plugs and wires
  • Coil Packs
  • PCV
Is it shifting good? Transmission fluid clean? Have you done anything recently that might cause the engine to dump some carbon? I am wondering if you have a cat on the way out?

How does the oil look? Is it getting dirty faster or does it last the same mileage as before?

It would really simplify things if you were able to pull codes. The ECU should not only hold any codes but also all the operating parameters for an extended period of time. I am surprised the dealership was not able to pull codes or find anything.
Coincidentally, I let them do the 90,000 Scheduled Maintenance the same time I took it in for the the CE light, so they did all the things you mention. It hasn't come on today, but it is cool weather and I didn't drive it that far. We'll see what happens.

And I'll call the dealer and try to get the code(s).
 

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Discussion Starter #5
And I'll call the dealer and try to get the code(s).
Now this is weird. I called them and they said there were no codes stored. Just the CE light is somehow being triggered, but there is no record of what triggered it. :wtf:
 

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Now this is weird. I called them and they said there were no codes stored. Just the CE light is somehow being triggered, but there is no record of what triggered it. :wtf:
They are full of crap and either reset the light without writing down the code or just ignored it.
 

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Discussion Starter #7
They are full of crap and either reset the light without writing down the code or just ignored it.
Not sure why they would do that. It seems to me they would want to know the code so they could tell me whats wrong so they could charge me to fix the problem. They don't make any money telling me its nothing and to just go away.

They also know that I am a regular customer and take diligent care of my vehicles so I would in all likelihood pay to get it fixed.
 

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For a 1998 and new OBD II compliant vehicle to throw the check engine light, a code is stored in the ECU.

Only way for no code to be there is that during retrieval, the mechanic accidentally clears the ECU fault memory with the scanner (quite common), ECU actually resets itself because the fault is no longer there after so many cycles or the actual ECU is faulty.

Take your pick of the above and go from there.
 

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I have to agree. The ECU will store all kinds of stuff forever unless it is cleared. Could have been accidentally cleared if the power was disconnected.

Next time the CEL comes on stop at Auto Zone and have them run the codes before going to the dealer. Just make sure they do not clear the codes before you can get it to the dealer.
 

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Discussion Starter #10
I have to agree. The ECU will store all kinds of stuff forever unless it is cleared. Could have been accidentally cleared if the power was disconnected.

Next time the CEL comes on stop at Auto Zone and have them run the codes before going to the dealer. Just make sure they do not clear the codes before you can get it to the dealer.
Sounds like a plan.
 

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Discussion Starter #11
OK.

I've had the CEL checked by three separate places and all show the same thing - no codes. Which tells me that something with the CEL system itself is screwed up. I need to get it fixed because if a real problem ever came along I'd have no way of knowing it unless the CEL is working properly.
 

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I think you have a mystery there. 3 times and no codes are stored at all. Maybe
you do have a glitch gremlin running around in that ECU. Has the dealer come up with any ideas? It must be frustrating for sure.
 

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Discussion Starter #13
I think you have a mystery there. 3 times and no codes are stored at all. Maybe
you do have a glitch gremlin running around in that ECU. Has the dealer come up with any ideas? It must be frustrating for sure.
Dealer hasn't a clue (not surprising). I do have a Unichip installed, but it's been on for years and never given me any kind of problem.
 
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