Problems after startup, a large number of error messages

For years, I've been having a problem with my Audi A4 Cabrio, 2.7 TDI, manufactured in 2007:
Sometimes, immediately after starting, the following problems occur:

Constant beeping, and the headlight leveling adjustment is displayed in the MFA (Multi-Function Display).
Settings on the multifunction steering wheel are accepted with a delay (e.g., changing radio stations, adjusting volume).
The automatic climate control lighting adjusts itself between bright and dim, and the fan speed fluctuates between stronger and weaker.
The window lifters are jerky when operated. The turn signals work, but the clicking sound is irregular. The GRA (automatic high beam) function does not work. Sometimes the low beam headlights also flicker briefly.

The only solution is to briefly disconnect the battery. Then everything works again, but only for a few days. It makes no difference whether it's raining, cold, or any other weather conditions. Not even whether the engine is warm or cold.
As I mentioned: the problems listed above always occur immediately after starting the engine - never while driving.

The error memory is completely full - but: where should I start?
Does anyone have any ideas?
Sure, here's the translation:

"Thank you in advance."

Andreas.

Hello,

"Have you been experiencing this problem for years? Has anything been modified or added to the vehicle?" Do you know the history of the vehicle?

Do the encodings match?

Where does the error come from?

01334 - Rear right door control unit (J389)
004 - No signal/communication - Sporadically.
01333 - Rear left door control unit (J388)).
004 - No signal/communication - Sporadically.

in a two-door car?

Has it ever worked since you've owned the vehicle?


There is also a TPI (Technical Problem Investigation) related to this issue... 2005366/13, which describes several intermittent errors occurring after a workshop visit, possibly related to an electrical component. Debugging...


I would start by deleting all the errors and checking which errors reappear and in what order.

- Check or replace the starter battery. Voltage drop during startup.
Please provide the text you would like me to translate from German to English.
Apparently, there are brief power interruptions.
at a speed of 96 revolutions per minute!

- Check the vehicle's ground connections for corrosion.

- Wiring harness, possibly for... Check for damage caused by martens.

- Check fuses and main relays.

- Check the wiring harness in the door opening where it passes to the A-pillar for any damage.

First, check the power supply and then the corresponding connectors of the components.

Is the water drain at the front of the engine control unit clear? Can water drain?


Best regards,

Michael.

Thank you, Michael, for your ideas.
I've owned the FZ for 6 years. I've had some intermittent, more serious starting problems occasionally, where the starter would turn, but the engine wouldn't start. After several attempts, it would eventually start without any problems. After several visits to the workshop, the fault was identified (a defective relay AH0951253).

Approximately three years ago, this current problem first appeared. At that time, I was on a road trip and visited a certified workshop. According to their information, they attempted a "reset" – which would be good if it worked, but if not, it would likely require a longer stay at the workshop and be more expensive. "The 'reset' seems to have worked. (I guess they disconnected the battery and connected the terminals.) That's been a good year so far - without any problems."

I've been frustrated for so long now - another "reset" didn't work either.

I have no idea what's going on with the rear door control module on the left/right side. The door control unit has not been modified.

A mechanic also mentioned that the control units are very sensitive to undervoltage. The battery isn't old enough yet to show any signs of weakness.

The water tank and engine control unit are dry. I disconnected, tapped, and reconnected the relays located there, and they seem to be working properly.

I'll try it with a new, powerful battery. If that doesn't improve things, then at least I'll have a spare battery on hand.

Next, I will replace the LWR.

Then I'm done. Then I can have a switch installed inside the car so that I can briefly disconnect the battery or disconnect it from the vehicle's electrical system.

Goodbye!

Best regards,

Jigsaw wrote:

I'll try it with a new, powerful battery. If that doesn't improve things, I'll have a spare battery on hand.

Since your problem only occurs when starting up:
When choosing a battery, don't focus on the largest possible capacity (e.g., 72Ah), but rather on the highest possible cold-cranking current (e.g., 800A).
The larger one is, the larger the other usually is as well, but depending on the technology, there are definitely differences.

Please pay attention to the cold-cranking current and the standard used. There are IEC, SAE, and EN standards. The values obtained for the same battery vary drastically depending on the different testing methods used.
IEC is the most stringent standard, and therefore naturally yields lower values. SAE is the simplest method, and therefore naturally yields high values.
I'm not exactly familiar with EN.
Manufacturers often specify SAE because the value is higher, which leads to better sales.
So, don't just look at the high numbers, but also question them.

PS: And don't believe any number from an unknown provider .
PS2: And only buy from places that actually sell a lot of batteries, or where the batteries are sold in a dry state. Unused inventory won't help you.

Regards,
Guste.

You're welcome, guste100. Your information has been noted.

Okay, quick update: I installed a new battery (Varta Blue Dynamic).
Before the renovation, a check was performed: When starting, the battery voltage dropped to 10.46 V.
After the modification: 11.36 volts. So far, so good.

Everything was working fine for a few days, but then, while driving, the TPMS (Tire Pressure Monitoring System) and headlight leveling symbols (along with the corresponding beeping sound) came on. Just for a moment, then everything will be back to normal.

The day before yesterday, the same thing happened again after starting the car. However, the error messages remained on the display throughout the entire journey. Additionally, the windows were jerky when operated. Unlike the old battery, the air conditioning was working normally, and the turn signal also functioned correctly.
The next day, after starting the engine, there were no more error messages displayed on the MFA screen - and this was without disconnecting the battery.

The hidden compartment also stopped working after the new battery was installed.

Conclusion: I don't have to disconnect the battery anymore - simply turning off the engine and restarting it should clear the problems/errors.

Next task: Replace the LWR sensor.

Let's see...

I would check the cables and connectors of the rear door control units (yes, they are present).
Have you ever experienced water leaks? If I'm not mistaken, there should be connectors located in the footwell area near the A-pillar on the driver's side. Please check this for oxidation.

Otherwise, the gateway might be faulty.

Best regards, Dago.