flg8r90

Hi Folks,

Driving along my CEL comes on and then the dash lights up like a chrismas tree. The low coolant indicator comes on and my temperature gauge drops to 0 (cold), and my a\c starts blowing hot air. I roll down my window and it sounds like my car is a fighter jet. I pull over to check the coolant level and the cooling fans are working overtime. Coolant levels are good, I don't smell any coolant leaks turn the car off. I figure it must be something electrical, maybe my some sending unit going bad... but does that have an effect on the a/c and coolant level? Is there a limp mode ? I let the car sit for a while and restart the car. Everything seems fine...drives fine accerates no stumbling nothing. Not even a CEL light. 20 mins later same thing. So I pulled over in a parking lot left the car there. Figure I'll go back and grab it in the morning, hope I didn't do any addition damage.... Any clues ???? Thanks for any comments or advice !


e

2004 A8L D3 4.2 V8

the_duke

First question everyone will ask:

VCDS codes?

JohnnyJ A6Q

By the temp gauge dropping to "0" then I say replace the G62 temp sensor, and yes all that you stated is what happens as "Safe Mode", no A/C, low coolant warning, fans at full blast, have done the same on my W12.

if you do not have a Ross-Tech for scanning either purchase one or ask on here for someone in your area for help with scan, it's a great tool to have and really is a must with these vehicles, I just did a coding and adaption for a friend today who had to replace headlight modules, that one trip to the dealer almost would pay for the cable if not in full......


.

flg8r90

Thanks !!!
I need to get the Ross Tech. Is it difficult to replace ? I've done some searching all I seem to find the proceedure to replace it one the W12 . It can't be in the same location ? Totallly different engine. Will i need to clear the codes when I'm done ?

MP4.2+6.0

Coolant temp sending unit. Yes, fans kick to high when sensor fails to be sure to protect motor. Still drivable.

On a 4.2 sender is in a metal portion of water line behind the cylinder heads and pretty low down. If setup with the intake tubes between the air box and throttle body is still something like my C5 4.2 was, that needs to come out to even see much of anything in that area.

Sensor is held in by a simple plastic clip. You pull the clip and then with some force sender pulls straight out. With a new o ring fit on the new sensor, it will be harder to get the new one in compared to pulling the old one out.

Yes, get the Ross-Tech VCDS. Std. needed tool for any modern Audi decent DIY.

JohnnyJ A6Q

Yes you will.

Also these are pics of a 05 A8L 4.2 V8, see the sensor circled.

Pothole5000

I did one of those on my 1.8t b6...... Well I had to bribe my friend as I literally could not fit my forearms into the area needed to reach it..... Glad to see Audi still hiding them behind the engine and crammed against the firewall.

Mister Bally

Keep in mind these photos are with the intake manifold removed. BTDT with the engine installed and the manifold in place.
TIP: buy an extra clip. Trust me on this.

flg8r90

Thanks everyone for all your help. Got the part installed and everything seems fine. Pretty straight forward. It's definitely a little difficult to get to but it can be done. This post helped also. https://www.audiworld.com/forums/a8-...r-ect-2816308/

Thanks to all those that contributed to that post as well.

Mister Bally

Glad it helped you. Nice to see that searching for prior posts works. For some individuals anyway.