Low engine oil pressure... And more.

[rtk8892]

Hey so my b6 s4 6 speed my is acting mad. Today as I was driving home from the gym the "low engine oil pressure" warning came on and the speedometer and tachometer both stopped working... Along with those symptoms, as I was accelerating (in any gear), as soon as I released the gas pedal the car jerked quite hard. I got it to the house, and found that the battery voltage was a tiny bit low (11.4v). Anyhow, with the car parked now it will start, then immediately die. It's almost as if it were an immobilizer issue but I don't have a dash light for it. I have an esp light up. Idk what the hell is up with this thing but it's driving me nuts. Anyone ever seen anything like this or have any ideas?

[rtk8892]

No one? Really? Damn

[caliizaktiv]

Open ended symptoms rarely get resolved without some tech details. Buy a vag-com and scan for codes.

[rtk8892]

The thing is, it's throwing a bunch of codes too that weren't there before. Like a lot. Is there a possibility it could be a bad battery/ ground/ or alternator?

[IslandHydro]

list the codes

[rtk8892]

I will, I'm at work right now though so it's gonna be a little while

[jakeoboy67]

the low battery voltage is what i'd focus on right now

[rtk8892]

Yeah I'm gonna pull the battery and bring it to advance auto tonight

[DarrenOman]

Someone once told me the more random codes the better, as it doesn't point to anything specific but something random like the battery or ground for example.
Good luck with the search. Do you get the battery/alternator dash light on?

Sent from my SM-G920F using Tapatalk

[rtk8892]

No I don't get any of those lights. I have a constant cel due to an o2 sensor, and that's the only dash light up until last night. I noticed on top of the engine just off to the left of the ecu there are two brown wires that lead to a ground point. One of the wires, the insulation has dry rotted and fallen off. Any chance anyone knows what those wires are and if they could play any part in this?

[badger.]

No I don't get any of those lights. I have a constant cel due to an o2 sensor, and that's the only dash light up until last night. I noticed on top of the engine just off to the left of the ecu there are two brown wires that lead to a ground point. One of the wires, the insulation has dry rotted and fallen off. Any chance anyone knows what those wires are and if they could play any part in this?

Read this thread:
http://www.audizine.com/forum/showth...res-connect-to

[rtk8892]

Yes those are the exact wires! Do you think this could be the cause of my problems? He didn't really mention any problems that it is causing for him

[924Carrera]

Yes those are the exact wires! Do you think this could be the cause of my problems? He didn't really mention any problems that it is causing for him

I'd clean and tighten that ground, but the wire flaking isn't your problem. The one with the insulation flaking off is the ground for the SAI pump and only for that pump. I guarantee that if you get into your harness, both the power and ground wires for that pump are flaking apart like that. Mine somehow avoided popping the fuse despite being basically bare next to each other, but I currently have my harness out and am replacing those wires to avoid any problems down the road. The fuse is a big 40 amp and is located inside your ECU housing.

Your SAI pump is an emissions related device that helps to warm the catalysts on cold start. Besides causing a CEL if it's not functioning, it won't cause any of the problems you mentioned, so I wouldn't worry too much about that ground wire. I would check, clean and tighten that ground just to be thorough though, as the OTHER wire on that stud (the one not flaking apart) is one of the main ECU harness grounds for the coilpacks and other parts.

[rtk8892]

Okay, the 40a fuse near the ecu had actually gone out once before, I replaced it about 3 weeks ago but checked yesterday and it's still good. Any idea what the 15a fuse next to it is for? I'm gonna reinsulate those wires I guess then work from there. I'm putting my money on a bad ground somewhere or a bad battery

[924Carrera]

Okay, the 40a fuse near the ecu had actually gone out once before, I replaced it about 3 weeks ago but checked yesterday and it's still good. Any idea what the 15a fuse next to it is for? I'm gonna reinsulate those wires I guess then work from there. I'm putting my money on a bad ground somewhere or a bad battery

Yes, I know exactly what the 15 amp is for. It's for the power supply of both cam adjusters and the relay for the coolant after-run pump. The fuse supplies power to a splice near it (wrapped up in the cloth insulation part of the harness inside the ECU box), which in turn feeds those components, and only those components. Why those 3 things are powered off a common splice and why the fuse for them is in the ECU box is beyond me, but it is. The main power supply relay, also in that box, is what provides the power to the fuse. I was having intermittent open circuit faults on those 3 parts so I replaced that relay. Haven't gotten the car back together yet thanks to a bunch of other stuff I'm fixing, but hopefully that takes care of it.

Edit: More to the story, that relay has two outputs that actuate together. One output feeds the fuse as I described. The other one provides power to all the coilpacks, and both cooling fan control modules (which are located near the front of the car). I was also having multiple/random misfire codes, so the relay starting to fail still seems likely.

[rtk8892]

So I actually pulled the ecu out of the car again just before, and disconnected it, as well as each relay and I sanded the connections a bit for better contact. After putting the ecu back in and the reconnecting the battery, the car fired up and was enough for me to drive it home. (I had to leave it at a buddies down the street yesterday). On the ride home the oil pressure light came back up on the cluster, as well as an airbag light, and my speedometer and tach were not working. Also the car was jerking upon letting off the accelerator. I'm so confused

[rtk8892]

Bump

[pandapod]

to me this sounds like a dead or dying alternator. First check to make sure you didn't lose your serpentine belt.

[rtk8892]

How would I test for this

[rtk8892]

Update: I went back outside to start the car up... It is doing the same thing. It starts, runs for a second then stalls out. There is no immobiilzer light present. I scanned it with vagcom using a foxwell nt500 and here are the codes it is throwing...

01-ENGINE

18010 Power Supply Terminal 30: Voltage too Low : P1602- Static - No Fault Type Identified

18048 Internal Contr. Module (EEPROM) Error: P1640

16524 Oxygen (Lambda) Sensor B1 S2: No Activity : P0140

18044 Powertrain Data Bus: Missing Message from Airbag Controller : P1636

18036 Powertrain Data Bus: Missing Message from Steering Angle Sensor : P1628

18057 Powertrain Data Bus: Missing Message From ABS Controller : P1649

18107 Powertrain Data Bus: Missing Message from Steering Wheel Electronics : P1699

18043 Powertrain Data Bus: Missing Message from A/C Controller : P1635

18058 Powertrain Data Bus: Missing Message from Instrument Cluster : P1650

16885 Vehicle Speed Sensor Implausible Signal : P0501

17978 Engine Start Blocked by Immobilizer : P1570

03- ABS BRAKES

18262 Powertrain Data Bus: Hardware Malfunction : P1854 Intermittent

18031 Powertrain Data Bus: No Communication : P1623 - Static - No Indication on Display

00778 Steering Angle Sensor (G85) - Static - Implausible Signal


08- Auto HVAC

01312 Powertrain Data Bus - static- Interrogate fault memory

09-Cent. Elect.

01312 Powertrain Data Bus - static - Interrogate fault memory

01326 Control Module for Multi-Function Steering Wheel (J453) - sporadic - No Communication


0F- Digital Radio

02635 Tuner Not Enabled Activated - static - No Indication on Display

15-Airbags

01312 Powertrain Data Bus

00474 Control Module for Immobilizer - static - Interruption

00532 Supply Voltage B+ - static - No fault type identified

17 Instruments

01314 Engine Control Module - sporadic - No communication

01316 ABS Control Module - sporadic - No communication

01312 Powertrain Data Bus - sporadic - Defective

25 Immobilizer

01314 Engine Control Module - sporadic - No communication

01316 ABS Control Module - sporadic - No communication

01312 Powertrain Data Bus - sporadic - Defective

46 Central Conv.

01134 Alarm Horn (H12) - static - No communication

00955 Key 1 - Intermittent

55 Xenon Range

00532 Supply Voltage B+ - sporadic - Signal too low

[AudiA4_20T]

Check J271 Relay in relay box. If it's malfunctioning it could be causing the ECU to short out.