It's completely overheating, but ironically the gauge stays in the middle. It's gotten so bad that there isn't a drop of heat coming from the vents. Once I got it home today (maybe 3 miles) it started steaming from under the hood the second I pulled into the garage, and that was w/ me shutting off the motor and coasting as much as possible. Here's a brief little FYI for ya:

03 A4 1.8T, roughly 88k on the clock
P3081 CEL code

73k - PCV and MAF have been replaced at stealership, then ECM flashed for cold start misfire.
76k - Oil change and shop noticed the thermostat and transmission cooler lines leaking. Replaced thermostat, waterpump (unspecified brand antifreeze) and timing belt.
80k - Coolant temp sensor, sparkplugs, cabin and engine filters, and battery replaced.

This is all I have for paperwork for his car. I've double-checked to make sure it is the green-top sensor up near the intake manifold, but I have yet to check the lower radiator neck to see what color sensor it is. Do you think I should try to refill and bleed the system to see if it's something else?

 

Overheating will destroy your thermostat, so try not to do that!! Maybe the coolant at the sensor is ok, but the coolant elsewhere is too hot. Where is the steam coming from? The cooling system is sealed so there shouldnt be any steam unless something is leaking. Its like the coolant is not circulating. Maybe a coolant flush? Was all of that service done at the dealer?? If not, maybe they used non G12 coolant, which mixed with the G12 and gunked something up.

 

The PCV and MAF work was done @ the stealership, everything else he's had done @ two or three different indy shop that aren't Audi specific. I can't tell what type of coolant they used, but the puddle sitting in my garage was orange-ish. Its not leaking, its just boiling over and coming out from what looked like two pressure-relief holes on the bottom of the overflow container. I could clearly hear it bubbling w/ just a little bit of steam coming from under the hood around the drivers headlight area and up-close to the windshield. I opened the cap on the overflow, and that is when the steam from those two holes really started to shoot out. This was kinda scary, so please no shooting to wild conclusions, but the oil light started flashing moment I pulled into my driveway. I've since let it cooldown and double checked the level. Its actually a little too high but at least its not milky.

 

What is the part you are calling the overflow container? There's not an overflow container and the system is completely sealed so anywhere you see steam is a leak.

 

P3081 or VAG 19537 Engine Temperature too low

Check Engine coolant temperature (ECT) Sensor. Check thermostat.

There was a service bulletin on this as well!



The problem plug allows air into the cooling system which can also cause the cooling system to loss effectiveness after warm up.

At least this is one more thing to check. Hope it helps

 

Hey Keagan, I can't view that scan because it's sized incorrectly. If you could redo it, that would be awesome.

 

The container closest to the firewall, right corner of the motor. It's where I would pour the coolant in, so I assumed it was also an overflow container.

 

that's the resevoir, it should always be full of coolant.

 

So i've got the bottom sensor out, the one that connects to the lower radiator hose. It's a gray top 2-pin sensor, but i'm not sure if there is a way to test it w/ a multimeter. I've PM'ed KeeganRX for a better scan of that TSB, but he doesnt seem to log on very often. I've tried using Google for TSB, but every site wants $ to view it.

 

After reading this post from Art @ http://tech.bentleypublishers.com/th...rt=15&tstart=0 i'm starting to wonder if in fact the sensor is doing it's job, doesn't need to be replaced and is telling the truth. I notice that when I turn the ignition on now, w/o the motor running, that both fans are running at full speed. It does this on initial startup too...the motor is dead cold, so why would they need to be on? I haven't driven the car in so long, so I can't remember if they shutoff/slowdown after driving for a while. Does anyone have a Bentley manual that they might be able to scan the pages from the article below so I can find these fuse boxes and connectors to test and apply voltage to them?

Posts: 2,733
From: Southern Maryland, USA
Registered: Sep 8, 2000
Re: P3081 DTC: Anyone help?
Posted: Jan 3, 2008 11:25 PM Reply


Good Evening, ChelleWithTheGTI,

You asked a bunch of questions, so let me tell you what I would do (or have done).

If we take it on faith that the coolant fans V7 & V35 do not run, I need to know if it is because the fans have failed or if it is because the operating circuit has malfunctioned.

Check fuses S164 & S180 (#3 & #8) on the holder on the battery FIRST.

Looking at wiring diagram #38/4 in the Jetta/Golf/GTI Service Manual (VG05), I see that if I unplug the FC Module J293 and apply battery voltage to the disconnected plug at T4a/2, both fans should run on low speed if the fans and wiring are OK. If not, inspect the wiring all the way back to the fans and apply voltage to the fan directly at the fans (T3a/2 and/or T3b/2). Since both fans run on high speed, we can safely say that the ground connection at position 12 is OK. If either or both fans do not run after this test, than I would suggest that the fans are defective. I don't have any recent shop experience to be able to say if this is a problem area, but I think it unlikely that both have failed at the same time. I think it much more likely that the FC Module is the problem. By the way, look closely for burned wiring and connectors at the fans.

With all that said, P3081 is not likely to be caused by coolant fan problems such as you've described. A stuck open thermostat, too high antifreeze concentration, or coolant fans stuck ON are much more likely causes. Also, I'm aware that some performance ECM chips upset and disturb this part of the diagnostics.

Keep us posted as you diagnose this problem, and be sure to update your profile to show a location.

Arthur LeBrun