Error Code: 16985 - Internal Control Module: Memory Check Sum Error


Registered User
Dec 2, 2008
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Cambridgeshire sometimes Hertfordshire
Guys I need help with the above VCDS code on a mates car. I've done a lot of searching and it seems to have happend on a lot of platforms including A3 8L/TT 8N/RS4/Golf mk4. There is a lot of info about the APR map causing problems but the ECU in my mates car is standard.

Ross-Tech say the following about the code:

Possible Causes

  • Engine Control Unit (ECU) defective
  • Flash ROM (used in aftermarket "chips") defective
Possible Solutions

  • Replace ECU
  • Contact aftermarket chiptuner for repair of their chip
As this is a standard ECU it looks like a new one will be needed!!!

Has anyone had any experience with this error on a standard Bosch ECU?
Got any more info about your mates car Neil? Make, model, engine code, year etc...

Got any more info about your mates car Neil? Make, model, engine code, year etc...


Yeah I was kind of avoiding that because this thread will probably get moved off to another forum never to be seen again!

He has a 2004 audi TT 150bhp FWD standard as the day he bought it. I've not checked the engine code but according to the following link it's likely to be either AUM or ARX
an incorrectly installed programme perhaps..
was it mapped before and running fine then this just happened?
Humm... difficult to tell without looking at it... if the ECU is damaged thats normally due to somebody having it out at some point and playing silly buggers...

At this point I would prob look to take the ECU out and open it up to see if there was any internal damage, dry joint or something...

nah it's cool, will leave it here for the experts to mull over. Usually you need to get a reflash due to corruption with aftermarket mapping/chipping. Might be worth him getting the ECU remapped to cure it, as its prob the same price as a dealer bios reset
LOL.... its like waiting for a bus :)

Bill should be able to shed some light on this Neil, faaaaaaaaaaaaaaaaaaaaaaaar more experience than me with this kinda thing...

The ecu is completely standard and unmapped. My mate bought the car from new and hasn't modded anything.

He said that the MIL came on after he hit a rather large pothole so a dry soldering joint or a loose wire would tie in with this!

I will get him to try the battery trick that has been used on a few other forums. ENsure battery is fully charged and touch neg and pos connectors together! Sounds a bit weird but I think he'll try anything if it saves him forking out for a new ECU.

Cheers guys, keep the ideas coming.