dylim

Hi All, my friend left her 2023 q5 phev in her garage for a year and never drove it...

The 12v battery is dead of course, only at 4V. Also the hybrid battery is at 0%. Earliest dealership appointment is one month out.

So I jump started the car, which drove fine (except for yellow CEL which was most likely complaining about the low voltage), and then replaced the battery.

Two problems:
1. After replacing the battery with a duralast agm 70Ah (OEM was VAO agm 68Ah), the dashboard lit up, which is expected.
Reset the BMS to register the new battery. But, I can't start the car at all, main codes are with the 01 engine control U011000, U041100, and 02 transmission U011000.
U011000 (Lost Communication with Drive Motor Control Module)
U041100 (Invalid Data Received From Drive Motor Control Module "A"

I found a TSB MC-10204962-0001 that says to establish a full bus deep cycle, clear the dtcs, full bus deep cycle, then check again, but that didn't work. Used bluedriver, OBD link MX+, and topdon artdiag 900 lite to try clearing the codes, no luck.

When I tried shifting gears, it stays in N and dashboard shows to put it in gear, start the car, something like that.

Just bought vcds hex-v2 from ross-tech. Does any one know what's the proper way to reset the modules?

2. The hybrid battery won't charge at all (MMI shows lock error), I saw that some people had luck spraying wd40 or contact cleaner onto the pin, and/or holding the plug slightly up until the lock engages, but no luck so far. Any one having the same problem?

dylim

Forgot to mention: I also tested all the fuses and the 3 645 relays under the footrest, they are all good.

MH62

Not what you want to hear but you may need to contact the dealership for advice. The vehicle should not be left with its batteries at 0% for more than 2 months. Here's what the manual says:

"Severely draining the high-voltage battery
can damage it. Once a O mi (0 km) electric
range is displayed, charge the high-voltage
battery within two months. If the stationary
time is unknown with the electric range at 0
mi (0 km), charge the high-voltage battery
immediately. Even if the vehicle is not used,
the high-voltage battery charge level will
naturally reduce over time. To avoid a total
battery drain during long periods without
use (more than one year), charge the high voltage
battery to the highest level possible
before discontinuing driving it."

dylim

Thanks, for problem 2 regarding the HV battery, we've made an appointment with audi. We tried charging it before but was faced with the same connector lock problem and she was in a hurry so we just gave up.

Right now I just want to get problem 1 solved - the car was running fine (with a jump start) before the 12v battery replacement. Now it won't even start.

Elvisfan

Even though the car is under warranty, it’s been abused. They may not cover any of this. We won’t even go into buying a new car and not driving it for a year.
You know that you probably didn’t do your friend any favors by trying to fix it yourself. Audi probably won’t warranty the car. Maybe they will.

dylim

Thanks. Well, there's a known problem with the charge port not locking. That is why it couldn't charge.

Elvisfan

That may be true. However, I don’t know what powers that port. If there is no power, the port can’t lock. Please let us know how this turns out.

dylim

The port was not able to lock even with power. In particular, when the oem 12v was still alive it had trouble locking, and after I have replaced the 12v battery with a new one and it still had trouble locking - I can see it attempting to lock three times, fails, and then solid red comes on. Mmi shows connector lock error.