1994 Audi cabrio, my check engine light comes on when the car warms up. What tool is used to determine what the problem is?

 

A paperclip

http://www.12v.org/maintenance/dtc.php

 

Thank you.

 

We've been waiting on the results of your codes. If you are having trouble with that, you could always go to a shop and get a code scan, probably $50-$60. A parts store usually doesn't have a sophisticated enough scanner and additionally you are an OBD-I vehicle. My experience on my '95 Cabriolet was to throw oxygen sensor codes. Replaced them and still same thing, car warms up and get a check engine light (CEL). This leads to the good advice I received from Crazy Russian and Loudgoldwing, that codes do not necessarily reflect the problem, just the symptom. In my case, that the O2 sensor was detecting the symptoms of O2 failure but it was not necessarily O2 sensor failure. Cleaned out the intake filter box, cleaned the Mass Airflow Sensor (MAF), replaced the noise damper gasket (or do the phone wire mod) replaced a few vacuum hoses and the problem went away. In short, cleaning and tightening up the system to prevent unmetered or poorly metered air in the system brought it back into acceptable parameters. I would recommend doing those things, as they can't hurt and are reasonably cheap, and then see how it goes. O2 sensors are pricy. Play it safe and use MAF cleaner on the MAF wire.

 

hubturn....not that you mention that, as of late, i hear a ticking sound coming from the harness attached to my airbox. Could this be related? Also, i tried the paper clip method..and it didnt set off any signals, the engine light remained on.

 

"a ticking sound coming from the harness attached to my airbox"

Hmmm... I admit, I've never heard that one. I am now intrigued.

Ya know? My Check engine light was triggered by my failure to notice a soft rubber seal between the corrugated 3" air tube and the hard 3" MAF housing connected to the airbox lid. When I pulled the big hose off the MAF housing to perform a MAF cleaning, I apparently popped that rubber ring seal loose and it fell out. When I was done, I put the hose back on, wrenched the little metal worm gear strap to tighten everything down, and started the engine.

The car drove really "boggy" for a block or two, then the CEL came on. Thinking I had fried the heated MAF element by spray-cleaning it, I uttered a few choice words to myself in the rearview mirror, and pulled back into my driveway.

After about 15 minutes of "Twist this and wiggle that," (on the car, not on myself) I noticed that the 3" intake pipe fastener was tight, but the pipe itself was loose where it met the MAF housing. So the ECU could only "feel" about 2/3 of the air hitting the MAF, and it was leaning my mixture waaaaaaay out to compensate. All this because I had a massive intake of unmetered air.

I think your noise discovery is pointing us in the right direction, here...

If you're hearing a ticking sound, it might be regular engine noise. But that engine noise is a lot louder when it is heard through air gaps in your intake path.

 

Thanks for chiming in.....the ticking is 100% coming from the harness on my intake, and i know think just be feeling it. How do you guys recommend i clean my air box and sensor, since you guys have already done this.

 

The ticking is probably the EGR vacuum regulator solenoid valve, or EVAP canister purge regulator valve, or one of the others located in that mess of vacuum lines near the air box. I've heard it too and you can feel it when you touch the device. Probably normal, but again, replace any vacuum lines that look frayed or brittle. Just blow out the air box, replace the filter if due, use MAF cleaner to spray the small MAF sensor wire. The MAF is the metal tube in the middle of the black air intake tube that connects to the air box. You have to take it apart to see it and clean it with the MAF spray. The noise damper is the big black plastic assembly that the MAF and it's hose attach to on the back of the intake manifold. The rubber seal between it and the intake manifold gets old and shrinks a bit allowing air that is not metered by the MAF to get in. It is not too expensive and is easy to replace. Just don't lose the two plastic grommets that ride on the intake manifold when you move it toward the firewall for removal. The oil breather tubes on the back of the head (black plastic)may have to be carefully disconnected, too. Search the forum.

 

Thanks for the reply's guys..its much appreciated. Furthermore, have you guys ever replaced the interior climate control light bulbs? I'm thinking of starting a new tread as i need to replace mine. Thanks

 

If you have the 3 **** manual climate control it is very easy to replace the bulbs.

Carefully pull the ***** off. Remove the two phillips head screws. Pull off the trim panel. You should now see three small bulbs.