Limp Mode Nightmare!! Please help

[BaronB5]

Hi guys my car has been in the shop for over a week now. My mechanics are stumped and so am I.

I replaced my old cat with an 034 hfc last week. I ended up taking it to my local shop because it sounded like an exhaust leak and low and behold the 034 supplied gasket from cat to dp had failed in one day! My mechanic replaced the gasket and everything looks fine. We went for a test ride and now I am only getting 5 psi which is weird because I had full boost with the exhaust leak. So I am somehow stuck in limp mode.

The car is running fine.
There are no codes.
No boost leaks.
Swapped ecu's.
Swapped MAfs.
Swapped n75.

Any ideas/suggestions?

2001 B5 a4 1.8t

[SN95Audi87]

Hi guys my car has been in the shop for over a week now. My mechanics are stumped and so am I.

I replaced my old cat with an 034 hfc last week. I ended up taking it to my local shop because it sounded like an exhaust leak and low and behold the 034 supplied gasket from cat to dp had failed in one day! My mechanic replaced the gasket and everything looks fine. We went for a test ride and now I am only getting 5 psi which is weird because I had full boost with the exhaust leak. So I am somehow stuck in limp mode.

The car is running fine.
There are no codes.
No boost leaks.
Swapped ecu's.
Swapped MAfs.
Swapped n75.

Any ideas/suggestions?

2001 B5 a4 1.8t

How does a thick gasket fail in one day? I got mine installed a few months back along with a new cat back and down pipe. Only thing I recall was the burning smell from all the new parts being broken in.

[BaronB5]

How does a thick gasket fail in one day? I got mine installed a few months back along with a new cat back and down pipe. Only thing I recall was the burning smell from all the new parts being broken in.

It split straight down the middle. I'll post pictures tomorrow but that was pretty lame.

[Blur2u]

Did you try clearing/resetting the ECU? Also unplugged the battery for a while and that should reset everything, see if the car goes back into limp mode.

[BaronB5]

Did you try clearing/resetting the ECU? Also unplugged the battery for a while and that should reset everything, see if the car goes back into limp mode.

I swapped in my old stock ecu and it still wouldnt go past 5 psi. No cel either

[BaronB5]

Turned out the vacuum line from intake manifold to my boost gauge had a hole in it. Everything is fixed. Thanks for replies!


Sent from my iPhone using Tapatalk

[Wrath And Tears]

I was going to mention that as a possibility, but the one time it happened to me it also affected my vacuum readings. The warmer the car got, the better the readings, I guess mainly because the line would swell with the heat helping to seal the leak.

[SN95Audi87]

It split straight down the middle. I'll post pictures tomorrow but that was pretty lame.

Turned out the vacuum line from intake manifold to my boost gauge had a hole in it. Everything is fixed. Thanks for replies!


Sent from my iPhone using Tapatalk

I guess it wasn't lame after all.

[BaronB5]

I guess it wasn't lame after all.

The lame I was referring to was the failure of the gasket after only one day. I'm calling them today to get my money back

[SN95Audi87]

The lame I was referring to was the failure of the gasket after only one day. I'm calling them today to get my money back

Ok I understand now. Very weird to see something high quality do that though.