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1994 Volkswagen Jetta Check Engine Light

Tiny
KARIEK
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  • 1994 VOLKSWAGEN JETTA
Computer problem
1994 Volkswagen Jetta 4 cyl Automatic 148000 miles

Check engine light stays on, checked the codes using the fuse/jumper (OBDI) and no codes appear and the light goes off; however, as soon as you remove the jumper the light comes back on. How can you figure out what to fix if there are no codes and the car runs great? I can't pass smog as long as the check engine light stays on.
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Wednesday, September 1st, 2010 AT 8:58 PM

5 Replies

Tiny
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Before any conclusion can be drawn, you should get a scanner hooked up, flash codes are not always reliable.

Mark (mhpautos)
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Thursday, September 2nd, 2010 AT 2:01 AM
Tiny
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Unfortunately, I have been to 2-VW Dealers, 1-Electrical Specialist and 2-Mechanics//Maint Facilities and no one can get any codes from their OBD 1 Scanner/Code Reader, they even try the OBD II for fun, that's why we also tried it the old fashioned way.
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Thursday, September 2nd, 2010 AT 7:50 PM
Tiny
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Hi there,

What you need to do first is test the fault gathering capabilities of the ECU, to do this you can induce a known fault, unplug the air flow meter and start the car, the ECU should set a code for this, if not there is a fault with in the ECU.

Mark (mhpautos)
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Thursday, September 2nd, 2010 AT 8:07 PM
Tiny
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We will try this tomorrow and I will let you know the outcome.
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Saturday, September 4th, 2010 AT 8:06 PM
Tiny
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OK, let me know how you get on.

Mark (mhpautos)
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Sunday, September 5th, 2010 AT 2:57 AM

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