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I was playing around with VCDS last night and decided to run a full scan. Much to my surprise, I had about six faults. Fortunately most looked to be from old issues that the Dealership had already resolved under the CPO warranty. Strange that they didn't go to the trouble to clear all the codes. I have driven about 100 miles since clearing and none have returned.
Here is the exception. I would clear this code and it would immediately reappear. Now that I am three months out of warranty, lol, I have no intention in heading back to the dealership. So, is this error exactly what it states (bad mount)? If I get under the car would it be obvious which one is bad?
No need to get under the car, unless it lost it’s hydraulic fluid there will be nothing to see.
The motor mount damping is electro-hydraulically controlled and there are a few things that can fail (see image). They still function without active damping, but it won’t be as effective- especially when in cylinder deactivation mode.
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Maybe ask the dealership for a copy of the last repair ledger including the codes posted.
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If the drivetrain mount fault was evident when they last serviced it under CPO...
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Need I say more?
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FWIW I believe actuator 1 is passenger's side, but its recommended to replace both as the other is likely to go shortly after.
For the S8 it should be
4H0199256AA
and 4H0199255AA for the Driver's side.
It looks like the S8 mount still comes with new sensor G749. For C model 4.0T's they reuse your old sensor now but the mount still costs the same. Ha.
Also I believe these have to be coded so you might be stuck going to the dealer anyway.
If they aren't torn/leaking they will hold the engine just fine, you won't have active damping effect but if you don't want to replace them you can simply have the car tuned to never use 4cyl mode.
Thats what I did but I mostly just hate the delay caused by it switching modes.
I feel certain that mine does not have cylinder deactivation whatsoever. Maybe it's just a S8 thing or I'm mistaken. Seems fine on the highway regarding low/no vibrations, etc.
I feel certain that mine does not have cylinder deactivation whatsoever. Maybe it's just a S8 thing or I'm mistaken. Seems fine on the highway regarding low/no vibrations, etc.
All 4.0 engines have it, it's easy to notice and induce if you know what you are looking for.
I feel certain that mine does not have cylinder deactivation whatsoever. Maybe it's just a S8 thing or I'm mistaken. Seems fine on the highway regarding low/no vibrations, etc.
As Striker mentioned you have CoD unless you have specifically tuned it out. (APR, DS1etc.) All 4.0T's have it regardless of model.
It is likely just not functioning right now because of your faulty mount. Since the failed mounts cannot counteract the 4-cylinder operation mode the system likely disables CoD altogether..
Geez these are expensive! Putting the possible coding aside, is this a DIY job?
Additionally, should I be concerned about my weekend travel plans (900 mile road trip)?
Anything is DIY depending on your skill level.
However it for sure is not "easy".
I am not sure how different the D4 platform is from the C7 but they have to remove the subframe brace and power steering rack and possibly lower the subframe altogether to access them. Requires an alignment when done too.
As I think was mentioned you can drive with the faulty mount and as you might have seen it may make nearly no difference. I personally would not leave it like that for long though.
10-06-2021, 01:37 PM
Mechanical Failure Confirmed
