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

[Boydie]

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]

Just ordered a new cam follower to change for peace of mind

06H109311
£34.30
Here tomorrow

 

[Peter Peter]

Just ordered a new cam follower to change for peace of mind

06H109311
£34.30
Here tomorrow

Or maybe high pressure fuel pump needs replacing ?

 

[Boydie]

@Peter82 who knows. The internals are Autotech so will see what it looks like when I have it off

thanks

 

[Boydie]

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