12.28.22 – Car stalled while idling in a Drive-Thru lane. Restarted and drove normally afterwards. Auto-Scan performed indicated the following relevant Fault Code:
008852 - Fuel Pressure Regulator Valve (N276)
P2294 - 004 - Open Circuit - Intermittent
I researched the N276 Issue here, as well as on multiple Audi forums and decided to wait until the cause was more conclusive. Though it seemed likely it could be the HPFP, it seemed it could also be related to few other things as well. Plus, it’s the middle of winter in NH, and I didn’t (still don’t) have a spare garage bay to chase an ‘intermittent’ issue while the care seemed to drive OK.
3/10/23 – Got a Check Engine Light in the AM (Engine warmed-up at highway speed) followed by an EPC Light shortly thereafter. Auto-Scan performed a few hours after the vehicle returned home indicated the following Engine Fault Codes:
008344 - Post-Catalyst Oxygen (Lambda) Sensor Correction; Bank 2
P2098 - 002 - Too Lean - MIL ON
000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low - Intermittent
000135 - Fuel Rail/System Pressure
P0087 - 008 - Too Low
Curiously, the O2 Sensor Fault had a date three days prior on 3/7/22, though I’m told there was no MIL until that morning. My son drives this S5 and swears there was no MIL prior, even after multiple inquires to confirm it wasn’t unnoticed and/or possibly obscured by the steering wheel. The following Auto Trans Fault code was indicated as well:
4765 - Functionality limited due to Engine Control Module
P1719 00 [036] - -
[Text noch nicht vorhanden - KFC_GBMOT-KFA_KSM]
Intermittent - Not Confirmed - Tested Since Memory Clear
I took the vehicle for a short/easy test drive to evaluate condition/drivability, and on the way back drove it a little more aggressively. Under moderate acceleration I observed an EPC Light as soon as the Engine exceeded 4000 RPM. As the vehicle had other pre-existing DTCs, I wanted to see which Faults re-occurred on the test drive. The post test drive Auto-Scan revealed a fault frequency increase on the following Faults:
000135 - Fuel Rail/System Pressure
P0087 - 002 - Too Low - Intermittent
4765 - Functionality limited due to Engine Control Module
P1719 00 [036] - -
[Text noch nicht vorhanden - KFC_GBMOT-KFA_KSM]
Intermittent - Not Confirmed - Tested Since Memory Clear
I was fairly confident the Bank 2 HPFP was the issue due to the Lean condition indicated by O2 Sensor Fault, but wanted to do some further troubleshooting to confirm and rule out any other issue(s) as my research tells me that Low Pressure at the Fuel Rail can also be related to issues with the in tank Low Pressure Fuel Pump (Lift Pump?), Fuel Filter and/or potentially the Low Pressure Fuel Sensor. I did some monitoring with the Engine running using the Measuring Blocks function to look at Fuel Rail Pressure, as well as some other parameters and observed that the Fuel Rail Pressure was approx. 25 bar. Having watched the Ross-Tech video re: Fuel Rail Pressure Testing w/ VCDS, I decided to check for a Fuel Rail pressure increase after the Engine was shut off as the Coolant/Engine temp was appropriate, however I inadvertently shut the Engine off (and the ignition) without hitting the ‘Close Controller, Go Back Button’ which I only realized after VCDS lost communication with Engine Module! After realizing my mistake I restarted VCDS but I was unable glean anything meaningful/definitive from looking at Fuel Rail pressure with the Engine off. After looking at Measuring Blocks and Advanced Measuring Values for several minutes, I attempted to start the vehicle, but it did NOT want to run at all. I made 4-5 attempts to start it, but it was only stumbling/barely running, and seemed it would stall, so I’d shut it off.
After letting the vehicle sit for 1 ½ hours or so, I decided to attempt to start it again. It started right up, though it ran a bit rough, however in addition to the MIL and EPC lights, I was immediately met with an alarming number of other faults indicated in rapid succession on the Instrument Panel (ESP Fault, Parking Brake Malfunction, TPMS Malfunction, ABS Warning Light) upon startup. I shut it down, planning to further investigate the following morning.
3/11/23 - I was concerned about Battery Voltage potentially having an impact, so I checked voltage first thing prior to connecting to the vehicle with VCDS. Voltage measured 12.3V at the Battery, and 12.2 at the under hood terminals. I then performed an Auto-Scan and it indicated the following ELEVEN new Engine Fault Codes, which were set when I had started the vehicle the prior evening:
005173 - Secondary Air Pump Relay (J299)
P1435 - 002 - Short to Ground
001112 - Evap System Purge Control Valve (N80)
P0458 - 002 - Short to Ground
004199 - Intake Air Switch-Over Valve (N335)
P1067 - 002 - Short to Ground
000256 - Mass Air Flow Sensor (G70)
P0100 - 002 - Supply Voltage
005715 - Please check DTC Memory of ABS Controller
P1653 - 001 -
005715 - Please check DTC Memory of ABS Controller
P1653 - 008 -
004763 - Fuel Pressure Regulator Valve; Bank 2 (N276)
P129B - 004 - Open Circuit
000256 - Mass Air Flow Sensor (G70)
P0100 - 004 - Supply Voltage
000048 - Oxygen (Lambda) Sensor B1 S1: Heating Circuit
P0030 - 004 - Malfunction / Open Circuit
000048 - Oxygen (Lambda) Sensor B2 S1: Heating Circuit
P0050 - 004 - Malfunction / Open Circuit
009217 - EVAP Leak Detection Pump Control Circuit
P2401 - 002 - Short to GND
There was also one new Engine Fault that was set when I attempted to start the vehicle previously, and it didn’t want to run:
008852 - Fuel Pressure Regulator Valve (N276)
P2294 - 004 - Open Circuit - MIL ON
In addition to the Engine Fault Codes there was the following new Auto Trans Fault code was indicated as well:
2505 - Torque Management Feedback Signal A
P2637 00 [039] - -
Not Confirmed - Tested Since Memory Clear
The following new ABS Brakes Fault codes were also indicated:
01314 - Engine Control Module
013 - Check DTC Memory
00473 - Control Module for Elect. Park/Hand Brake (J540)
013 - Check DTC Memory
As well as the following Parking Brake Fault Code:
01314 - Engine Control Module
013 - Check DTC Memory - MIL ON
In reviewing the Freeze Frame data, all of the ‘New’ Faults occurred with a Battery Voltage of less than 12 volts (basically collapsing from 11.7V to 11.2V before the Alternator picked up the voltage.
3/12/23 - I do not have a Battery Charger suitable for an AGM Battery, so I connected a Booster Pack to the vehicle prior to doing anything further today. I then connected to the vehicle w/ VCDS, decided to clear all DTCs with the Ignition ON and then ran an Auto-Scan. I had hoped to clear any DTCs that were purely related to any low voltage condition that may have occurred. After the Auto-Scan I started the vehicle, and reconnected w/ VCDS. Many of the DTCs returned, and I ran another Auto-Scan to document the changes. While the Engine was running, I checked Fuel Rail Pressure and it was approx. 6 bar, while the specified pressure was 30 bar!
At this point I’m pretty certain I need to replace both HPFPs, but due to all the other Faults that occurred, I’ve got a number of questions/concerns:
- Did I somehow damage (fry?) the ECM when I shut the Engine off while using the Measuring Blocks application in VCDS? I ask because the instructions in Ross-Tech Fuel Rail Pressure Test video, specifically state “Exit out of the Engine Control Module, Click on Done-Go Back, then Close Controller-Go Back to exit out. When VCDS is No Longer Communicating w/ the vehicle, it is now ‘Safe’ to shut the Engine Off”. Is it NOT Safe to do otherwise, as I inadvertently did?
- Were the add’l Faults likely caused by attempting to start the vehicle with low Battery Voltage, and could this have potentially caused any relay(s) or fuses to fail as a result, as many of those Faults still remain? Could that have also created a terminal condition for the HPFPs, both of which now have DTCs indicating they have failed Regulator Valves and a resultant significant drop in Fuel Rail Pressure?
- What should I do here, and what should I do first as a next step? At this point I have not gone down the path of checking any relays or fuses (I’m not even 100% sure where I should be looking). I’m ready to move forward with purchasing new HPFPs ($1000 from FCP Euro) if that’s advisiable, but I’m not 100% sure what to do.
What other issues do you think I’m dealing with here? Any help and/or guidance from the forum experts would be MUCH appreciated. Thank you.
Due to limitations in the forum software, the final VCDS Auto-Scan is posted in the separate post.
ETA - This is cross posted on the Ross-Tech forum as well
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