MKB Error: "AHH" - Strange Emergency Mode

Hello everyone,

I searched extensively and found many valuable posts, but unfortunately, I couldn't find anything related to what happened with my AHH in the last two days.

Problem:

As the title suggests, my Passat is running in limp mode, but not from the very beginning.

Problem description:

When accelerating, the emergency mode is activated in the 3rd and 4th gears, always between 2800 and 3000 RPM. Strangely, it no longer allows speeds above 140 km/h.

So far, so good. I've read a lot in the forums and researched several possible solutions. HOWEVER: If I accelerate, paying attention to keep the RPM below 2800 in 3rd or 4th gear, and then shift to 5th gear *before* the limp mode program activates, the engine runs normally.

This morning, I did a test, and according to the speedometer, the car reached a speed of up to 190 km/h (of course, without any error messages or the aforementioned limitations).

I've checked the hoses as far as I can tell, and they seem to be okay.

If a turbocharger is defective, would the engine always be in a limp mode?


Unfortunately, I don't have a diagnostic tool to post logs here, but perhaps we can jot down some clues.

As always, I am grateful for your help.

Best regards,

Hello,

As I can see, no one has had such a problem, or I may have missed a similar experience in the search . Well, I'll have to take another look.

Anyway, I had the timing belt replaced today and took it for a short test drive on the highway, during which I drove at full load for about 5 minutes (using the method described in the first post).

MIRACLE After that, everything was fine, so there was no limp mode, no matter which gear I was in, and even above 3000 RPM. I'm a little relieved now, but:

I'm really curious to know what it was. Why did the engine run in emergency mode?

I know, I know, I'm just asking, and there could be hundreds of possible answers, but I still want to know, whether it's a guess or the correct answer. After all, for me, even a guess is a learning experience, since I can't even begin to guess what it might be.

Unfortunately, no one came up with a brilliant idea .

Thank you for your understanding.

Hi,
If my crystal ball (which I recently bought for 15 euros on eBay) doesn't deceive me,
It shows (or showed) an error code related to 'turbocharger pressure control deviation' in the error memory.
Either the VTG adjustment is stuck, or there's something wrong with the pressure transducer's diaphragm.
(assuming that the hose connection is actually in good condition / leak-proof).
As long as you increase the speed gradually, the adjustment will catch up.
and the emergency mode does not activate.

Hopefully, you'll remain in this state (I'm afraid that might not be the case).

Best regards, Rudi.

Thank you for your answer, Rudi .

Okay, I'm going to use the search function with the terms mentioned above, and I'll probably have some success.

However, I've noticed that if I only do city driving for several days, it seems to 'clog up' again, but then one trip on the highway clears it right up.

Well, it seems like everything is useless without a VAG-COM, so I guess I have to get one.

Whatever, I want to thank you again for your help.