jdip

2013 q5 prem plus with 39425.

Went to work. Got out and noticed NY A/C was blowing hot air. Thought it would go away. Same thing happened on my 09 premium last summer on really hot days but was intermittent problem and would go away if I recycled the ignition.
Low and behold 2 days in my relatively new vehicle with no A/C.
Recent history:
The car just got back from a month at the body shop after front r panel,and both passenger side door replacement from side swipe. Had to return the car as they left a parking sensor unplugged. Got it back a second time with the back up camera being flakey and wiping off and on like a bad vcr connection. Through the a/V fault code. Though I had video of the problem dealer couldn't replicate. Despite me clearing the fault code with carista app and it kept coming back dealer cleared it and it stayed.
2 days later made some changes in carista like deleting the signal wink, activating ambient floor lights and windows with remote. I had the hidden mmi menu active for 2 days and *****I ABSOLUTELY DID NOT TOUCH ANYTHING I WASNT FAMILIAR WITH OR THAT WAS NOT IN INTRUCTIONS TO ENABLE INTERIOR FLOOR LIGHTS.****
The a/c was actually broken before I activated those changes and I didn't notice because I did them at night and have a 3 minute commute to work. So theoretically the only changes I made BEFORE the ac screwed up was activate hidden menu and delete turn signal wink. I didn't go into the hidden mmi menu for the first time until after the a/c wasnt working
This is the fault code I got when I rescanned. Again carista cleared it and it kept returning with no changes to my a/c. I've tried many things with no luck.
Searched these codes but seems like it could be one of many things. Most common answer is the temp sensor. It's the 00457 fault code that concerns me.
I'm worried the ECU is going because of the backup camer a glitch now these what appears to be electronic faults for the A/C.
Ideas. Suggestions? By the way the other fault codes for key and infotainment were ghosts and never came back. Those aren't a problem.

Redd

Sounds like damage to the electrical system or bus, possibly something loosened, giving an intermittent short or ground fault, possibly something torn or chafed. A month at the body shop...dealer? A month is a lot of body shop time, in any case. Any structural work? Any welding? Which I ask because arc welding can incidentally blow out electronics of all kinds on the attached vehicle.

jdip

Independent body shop however it was an Audi Certified body shop. No structural damage just superficial replacement of panels and doors, and painting. No welding to my knowledge. Month was pretty much because of the at fault insurance company dragging butt like a dog with worms.

Dealer said they replaced pressure sensor under warranty and its fixed. But I'm still concerned all this is happening so close to each other to be too much of a coincidence

Redd

A good "whack" can impact many things. If passenger side panels were impacted, there's usually wiring running alongside them, and ECU components, isn't there? If it wasn't such a PITA, I'd want to tear off all the interior trim panels, and test hands-on that everything was secure and unchafed.

But I'm sure Audi has a procedure for refuting the Carista readouts. (sigh)

Well, at least they should be able to read the same OBDC codes.

jdip

Oh I didn't tell them crap about me doing my own obd scan. The advisor said they scanned and found fault codes. I asked them which ones and they matched mine. I hate my Audi dealership. Both advisors are complete d bags and are very disrespectful. When I was in there for the camera they said "you don't need the print out" when I asked for the vagcom print out. I said yes because if the camera glitches again i want hard copy proof of which codes it through the first time.
They claim when it was in for the camera last week they checked the module for the camera and it was fine since the body shop removed the tailgate I thought they could have nicked something or left the wiring harness loose. Seems like they did actually check it because my interior cargo R side panel was taken off because my canvas liner cover was put back on crooked. I KNOW they would not go back to front and recheck wiring though. The service advisor said there was no chance this is related to body work.

Is the pressure sensor on the L or R Side of the car? I believe it's behind one of the headlights?

DimaA6_ABC_Kiev

This sensor failed on wife's Q5 without any accident. Dealership guy said they had plenty of such issues not only in Q5's. ETKA says after some date sensor has different version, looks like VAG has redesigned them.

spijun

Exist pressure sensor S/N: 4H0959126 dropped 11.02.2013 replaced with 4H0959126A
Used in: A3, A4, A5, A6, A7, A8, Q5, R8, RS4, RS5, RS6, GOLF , TOUAREG, OCTAVIA, LEON

Redd

Sadly, replacing an A/C pressure sensor (any brand, any system) will also require pulling a hard vacuum on the system to recover the refrigerant, which probably will go to the recovery bottle and have to be replaced with new refrigerant...making that simple sensor an expensive job.

Perhaps the genius who figured out a TPS without sensors buried in the wheels, could be put to work on making a "noninvasive" AC system pressure sensor as well. That would be a piece of exquisite engineering.

Keep the p/s, keep the p/b, keep the automatic, the tunes and hell, even keep the heater. Personally, on a hot humid August day? The AC means more than all the rest to me!

MurrayA4

Most Audi's , my previous B6 A4, for one, are well designed in this respect.The Ac.pressure switch can be removed and replaced without having to remove the refrigerant gas.When you remove the switch there is a valve at the base of the threaded housing which shuts and prevents leakage.Makes sensor replacement easy and cheap.

Redd

I think the trade-off is that the valve itself now doubles the number of potential leaking points. Clever idea if it is reliable though. Or if the pressure switches are so prone to failure. (I'd expect that kind of switch to be good for 20+ years.)