Lucid

TIA to anybody who reads this whole thing.

I have the APR chip (TBox). About two months ago, I went from Stage 1 to Stage 2+ (downpipes/catback) and flashed my ECU with the Stage 2+ software. I hear that it's not really necessary with my AWE downpipes as they relocate the O2 sensor, but I figured what the hell.

Aside from the timing issues in the upper RPM range, everything has been peachy until about 2 weeks ago when I get a CEL. Everything felt fine, so I wanted to fix this myself instead of immediately rushing to the dealer. I prefer to avoid interactions with the dealer because I'm modified. I ordered the Ross-Tech Vagcom so I could diagnose this myself. It finally got here yesterday and when looking at the codes, the only one I found was this (not verbatim):

Mismatched ECU checksum

Now I know what a checksum is. What this means is that my ECU either got corrupted or wasn't properly hacked by APR to generate an authentic checksum. Since it was about 6 weeks before I got the CEL after flashing my ECU, I figured the most likely idea was that it got corrupted somehow--either through a static shock or perhaps the EMCS program switching feature corrupted the data somehow.

I reflashed my ECU fresh again and did a fault code erase, TBA, the works. The CEL went away and I shouted "Eureka!"

Then this morning on my way to work the CEL showed up again. I haven't had a chance to use my Vag again yet, but it bummed me out and I thought I'd share it with all of you.

Has anybody experienced anything like this? I feel like ditching work to go figure this out (but naturally I won't).

My car is running the same (not in limp mode). Is it possible my CEL isn't even related to that fault code? I'm just over 21k miles, and as I did my own oil change, the dealer said it wasn't necessary to come in for my 20k service. My car has been complaining about needing service for a while now. Could the CEL just be even further nagging by my car to be taken to the dealer?

Mark P

I called APR and Jeremy said he believes it to be a failing memory device within the ECU, not part of EMCS, nor chip-related. He said they have seen this before and it can get to the point where the car won't run at all. Before I shell out the $ for another ECU, I'd like to hear from anyone else that's had this issue and if this is indeed the case, or anyone else's thoughts.

This is my original ECU, with 67k miles on it, and it was chipped back at 20k, and I reprogrammed it 2 weeks ago with the Stage3 programming. I've never seen this error until now.

If I try to "clear codes" with VAG, it goes away for a second while VAG is checking for codes and sure enough it immediately comes back. Is this how yours is? The Check Engine light will then come on after about 50 or so miles driving with it being registered.

I believe the code is:
"internal control unit - memory check sum error"

Here's a post of mine on the VAG forum...<ul><li><a href="https://forums.audiworld.com/vag/msgs/1117.phtml">https://forums.audiworld.com/vag/msgs/1117.phtml</a</li></ul>

Lucid

If it's unique to APR chipped ECUs, couldn't we point a finger? I'd rather not start leaping to conclusions, especially as so far it's just the two of us with this problem.

But if it's simply a faulty ECU memory controller or memory chip (or something), we're SOL about getting it replaced by the dealer as it's going to be quite clear we voided that warranty on this very component. (That's not going to happen, no way, no how.)

It might be just the push I need to switch to GIAC or ABT though, if I'm going to have to buy a whole new ECU anyway.

Lucid

My light came on again after less than 10 miles driving. &lt;eom&gt;

Singletrack

Checksum errors = corrupted data = who knows what.

-st

The R

before opening up the ECU to hook it up to the home programmer?

If you have to buy a new ECU, can't you just have the APR chipped moved to the new ECU? You might want to wait for the v3.4 to come out before making your final decision to switch. ;-)

Mark P

I was grounded, and always grab the ground plane of the ECU first

mpwolf

It's pretty odd that the first two times this has been posted it's been on APR T-box cars.

The R

some corrupted code on their site or something?

George @ BostonAudi

You could have a bad image without the ECU necessarily hitting the code instantly, or having a problem with the car running.