Buzztt

having been told by a tech that the problem is very likely a loose filler cap and having noted that the filler cap was indeed loose, tightened it up and then a day later the light went out, im pretty sure i know what the problem was.

i bought a cpo for a reason, so i dont have to freak out if a light comes on, if the problems arises again ill take it to the dealer and they can fix it.

my friend has vcds and he is coming to my house so i can do all the tweeks i want, theres no point buying one.

Richard Solomon

CEL (Check Engine Light/lamp) is a misnomer, I think the OBD spec calls it the MIL (Malfunction Indication Light/lamp).

Actually this is already true - depending on the malfunction detected the MIL may be set immediately or only after a set # of occurrences. O2 sensors are absolutely filtered that way - glitches are filtered repeatedly before the MIL is finally set. I also know misfires are also similarly filtered, but I can't speak to detection of an injector failure - if that even happens. My car was misfiring like a big dog and the MIL wouldn't set for several minutes. VCDS showed the misfire codes immediately and the MIL wouldn't set for some time.

The gas cap AFAIK is actually also "filtered" but since you don't generally touch the cap during a drive cycle, it feels like "once" to you The car pressurizes the fuel system at various times via the LDP (Leak Detection Pump) looking for leaks, and depending on the magnitude of the leak (rapidity with which pressure drops) it sets small or large leak codes and triggers the MIL after some number of events. (I haven't looked lately, but large leak might be immediate MIL, I do know small leaks don't necessarily set the MIL.)

snagitseven

CEL, OBD, MIL, ESC, ESP, ACC, DIS, LDP, ASR, DSR, EPS, ABS, GPS, RPM, PSI, TDI, TFSI, ECU, HUD, HID, LCD, OEM, VIN, TPMS and the beloved MMI, just to name a few.
OMG, what is an Audi neophyte to do with the alphabet soup of acronyms? LOL.

Mike_L

Some of those I don't know
CEL - Check Engine Light,
OBD - On Board Diagnostics,
MIL - Malfunction Indicator Light,
ESC - Electronic Stability Control,
ESP - Electronic Stability Program,
ACC - Adaptive Cruise Control,
DIS - Driver Information Center,
LDP - Lane Departure Program, ?
ASR - Acceleration Slip Regulation,
DSR - ???,
EPS - ???,
ABS - Antilock Braking System,
GPS - Global Positioning System (or Satellite),
RPM - Revolutions Per Minute,
PSI - Pounds per Square Inch,
TDI - Turbo Diesel Injection,
TFSI - "Turbo" Fuel Stratified Injection,
ECU - Engine (or electronic) Control Unit,
HUD - Heads Up Display,
HID - High Intensity Discharge,
LCD - Liquid Crystal Display,
OEM - Original Equipment Manufacturer,
VIN - Vehicle Identification Number,
TPMS - Tire Pressure Monitoring System,
MMI - MultiMedia Interface

snagitseven

DSR - Driver Steering Recommendation
EPS - Electronic Power Steering

and just in case:
OMG - Oh my gosh (or God)
LOL - Laughing out loud (or can be Lots of love)

kevin880

I went to dealer today and the problem is a knock sensor is bad. It requires 4 hours labor and the removal of the manifold.Time to get rid of the car.

Richard Solomon

Are you out of warranty? I'd try escalating that if so, knock sensors shouldn't just "go bad", and I'm a bit suspicious of that diagnosis anyway! What were the codes thrown?

While this highlighted part is key (and I didn't notice it in your earlier post), you do know what they say about what happens when you ****u*me... Definitely have your friend pull the codes if a VCDS is out of your means or whatever.

Mike_L

I'm not seeing 4 hours to swap that. Access seems to be pretty good, though tight, from underneath. Its a single bolt. They should be able to remove it and put in a new one without removing the manifold.

Anyway, it should be covered under the warranty. Knock sensors aren't wear items. They don't just wear out. If its bad, it was defective. If the first dealer won't fix it, go to another one. (Tell me you're on Long Island and went to Biener)

Buzztt

So having seen symptoms of a problem, taken measures to correct the problem and then the cel light goes off letting you know it's no longer a problem you still wouldn't be satisfied, fair enough, each to their own. if my car wasn't under warranty I would check the codes and probably be more concerned but I'm gonna 'risk' it and assume the loose has cap was the issue and leave it at that, if the light comes back on again I'll take it to the dealer and let them figure it out.

And a vcds isn't out of my means, I just don't feel it's necessary to buy one for a car that's covered by warranty, and will likely be traded in within the next two years. I'lll happily spend time money and stress when it comes to my other cars which are out of warranty and are modded so need to be monitored and babied but not for a CPo Audi.

Mike_L

I'm with Richard. When the light comes on, the scanner gets hooked up, first thing. Just the Actron though. Can't be bothered checking stuff with VCDS all the time.