2014 S5 B8.5 - Orange EPC light followed by stall

[rzwood]

Hi,

My S5 displayed an orange EPC light on the dash driving home from work. I was going to look it up when home, but then the car lost power and completely stopped. After a few fruitless attempts to start, it eventually started and I continued only for the same thing to happen within another mile. After several repeat incidents, I was able to get home.

I have the Ross-Tech VCDS software so I hooked it up and these(below) were the faults listed:

Is anyone able to diagnose the issue ? More relevant is whether it's fixable at the road side or do I need to have it towed to a garage ? Do I need an Audi dealer/specialist ?

I'm not sure if the fault was triggered by the heat as it's been hot today in the UK(34C) and I could start the car after leaving it a few minutes. I don't think I should try to drive again for fear of the same fault.

Any advice appreciated!!

Thanks,
Richard

6238 - Fuel Rail/System Pressure
P0087 00 [00100000] - Too Low
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 2
Mileage: 121115 km
Date: 2025.07.01
Time: 15:35:21

Engine speed: 1269.00 /min
Normed load value: 29.8 %
Vehicle speed: 65 km/h
Coolant temperature: 96 ∞C
Intake air temperature: 44 ∞C
Ambient air pressure: 990 mbar
Voltage terminal 30: 12.796 V
Unlearning counter according OBD: 40
Engine speed: actual: 1248 /min
MAF_ENVD: 375.84705 mg/stroke
Coolant temperature (unfiltered): 94.50 ∞C
FUEL_MASS_REQ_I_CTL_ENVD: 28.265625
FUP_ENVD: 1358.5177 hPa
FUP_EFP_ENVD: 1363.83 hPa

16903 - Vapor Bubble Formation in Low-Pressure Fuel Circuit
P125B 00 [00101100] - -
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 8
Mileage: 121115 km
Date: 2025.07.01
Time: 15:35:54

Engine speed: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 13 km/h
Coolant temperature: 95 ∞C
Intake air temperature: 51 ∞C
Ambient air pressure: 990 mbar
Voltage terminal 30: 12.898 V
Unlearning counter according OBD: 40
Engine speed: actual: 0 /min
MAF_ENVD: 0.00000 mg/stroke
Coolant temperature (unfiltered): 92.25 ∞C
Engine: operating status: ES
FUP_EFP_ENVD: 2045.74 hPa
Vehicle speed: actual: 8 km/h

11010 - Fuel Pump
P3043 00 [00101100] - Mechanical Malfunction
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 6
Mileage: 121092 km
Date: 2025.07.01
Time: 15:18:56

Engine speed: 2464.00 /min
Normed load value: 56.9 %
Vehicle speed: 20 km/h
Coolant temperature: 96 ∞C
Intake air temperature: 43 ∞C
Ambient air pressure: 990 mbar
Voltage terminal 30: 12.491 V
Unlearning counter according OBD: 40
Engine speed: actual: 1184 /min
MAF_ENVD: 76.25882 mg/stroke
Coolant temperature (unfiltered): 93.00 ∞C
Engine: operating status: PUC
FUP_EFP_ENVD: 5455.31 hPa
Vehicle speed: actual: 37 km/h

14812 - Fuel Pump
P308D 00 [01100101] - RPM too Low
Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 1
Mileage: 121117 km
Date: 2025.07.01
Time: 15:46:38

Engine speed: 1140.00 /min
Normed load value: 7.8 %
Vehicle speed: 35 km/h
Coolant temperature: 94 ∞C
Intake air temperature: 52 ∞C
Ambient air pressure: 990 mbar
Voltage terminal 30: 13.202 V
Unlearning counter according OBD: 40
Engine speed: actual: 1120 /min
MAF_ENVD: 92.60000 mg/stroke
Coolant temperature (unfiltered): 94.50 ∞C
Engine: operating status: PU
FUP_EFP_ENVD: 4773.4 hPa
Vehicle speed: actual: 35 km/h

Readiness: 0000 0000

[Steve Q]

I think this is pointing to the fuel pump. I'd suspect the high pressure fuel pump. But this doesn't explain the epc light. 

The alternative thing could be to get the battery tested to see if it's working correctly. Just in case it's failing and throwing up fault codes. 

[rzwood]

Thanks @Steve Q, battery was replaced recently. I did google some of the fault codes and this looks a good match for the issue that occurred yesterday.

https://static.nhtsa.gov/odi/tsbs/2017/MC-10127910-9999.pdf

Referenced from this article

https://www.audizine.com/forum/showthread.php/981284-Fuel-Issue-Diagnostics

I haven't tried the car yet today but it is cooler so it may be ok at least for me to get it to a garage.

Thanks
Richard

[Steve Q]

Please keep us posted on how you get on 

[cliffcoggin]

4 hours ago, rzwood said:

 battery was replaced recently.

Was it coded to the car? It needs to be.

[rzwood]

Yes, the new battery was replaced following AUDI/VW BATTERY CODING USING VCDS. This was done a few months ago now and car has been working perfectly since(even the Start/Stop system began to kick in again as it hadn't been with my ailing battery).

Latest is that I booked the car in at Audi Guildford on Monday for a diagnostic appointment(£150) and included the fault code output I posted here.

I took the car out for a brief road test earlier and even after driving it quite hard(>5000 rpm), there were NO further issues, NO EPC warning light etc., so all seemed good(I wasn't driving hard when the fault happened).

My opinion is that the fault was triggered by the hot weather we had yesterday in the UK, that coupled with possibly some part of the fuel system that has degraded over the past 11 years.

Hopefully, Audi(Lookers) can shed some light on whether anything needs replacing.

My main concern was whether the car was still drivable after yesterday and all I can say is so far so good. I'll be wary the next time I'm on a long run though 😬.

Any comments ?

Thanks,
Richard