PFL S3 - Start/Stop system fault leading to fuel rail/pump pressure low

Boydie

S3 8V DSG
VCDS Map User
Hey guys

Seems to be the first major fault with my 2014 S3 since ownership this last 3 years.

Bit of info on my S3 in case you don't know or remember:

2014
47k miles
Revo Stage 3+ (important: entire LPFP and HPFP internals changed around Oct 2018)
Meticulously maintained
etc...

Just this last month, an "automatic start/stop: system fault! Function unavailable" notice comes up on the DIS.

At the time, I went another drive, start/stop worked fine, turned off engine and on, etc... went away.

Next time it happened, I drove up to a junction, engine stopped as normal but I immediately pressed accelerator to go, so the engine stopped momentarily and started again. Next thing, engine management light came on.

Plugged on OBD11 and the following showed up on engine:
  • P008700 Fuel Rail/System Pressure too low
  • P308D00 Fuel Pump Engine Speed too low
And this has been the case the last 3 times the light has come on. My theory is that because there is an issue with the start/stop, the car then thinks fuel pressure is too low hence the two above faults.

Only seems to happen after the engine cuts off for start/stop and when I have it turned off manually, the engine light never comes on.

So, on initial Dr.Google diagnosis there are a few things to check:
  • I have read about a sensor to do with start stop that could be faulty but I have no part number
  • Could be an issue with the cam follower (which I changed in Oct 18 for the HPFP internals)
  • Could be an internal cam shaft issue but IMO I don't think so as the car performs perfectly fine 70+ miles a day
I think I will change my cam follower for peace of mind. Did this all the time on my 8P S3 as precaution.

Any other suggestions or advice from previous experience?

Thanks
 

Boydie

S3 8V DSG
VCDS Map User
Just ordered a new cam follower to change for peace of mind

06H109311
£34.30
Here tomorrow
 
Last edited:

Boydie

S3 8V DSG
VCDS Map User
@Peter82 who knows. The internals are Autotech so will see what it looks like when I have it off

thanks
 

Boydie

S3 8V DSG
VCDS Map User
It has been suggested to check position of my LPFP as it may have dropped in the basket - will hopefully get a chance to check this out this weekend

I will fit the new cam follower also
 
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