Unknown Fault Codes Help Please! + 0 Boost?

[AudiA4B596]

Hey guys,

My cars been great this summer up until a few weeks ago when I lost boost (from 7-8psi down to 0-1psi) and feel like I have no power or turbo at all, so I ran a vagcom check and out came these fault codes in the picture I've linked. I have no idea what they are? Maybe someone could help me please?

http://i1171.photobucket.com/albums/r554/TheTommy87/20130710_185914_zps0c29c9b6.jpg?t=1374191892

I'm just wondering, but my friend linked up his vagtacho to my car around the same time and it sent the immo nuts. Had to use vagcom to get the immo to behave again. Could this have anything to do with it, or is this just a coincidence? I have a feeling he did something with the eeprom maybe?

I've checked around the engine compartment for signs of leakage all around the air hoses (turbo, air filter/maf and intercooler hoses) and pressure/boost pipes (intake manifold, turbo and gauge lines) and also the fuel line and pump but couldn't see any obvious leakage. Everything seems ok. Is there any others or anything else I could look for?

Could the boost problem be something to do with the DV, wastegate or exhaust?

Many Thanks,

Tommy (AudiA4B596)

 

[jbh]

I looked up the fault codes
try googling them as well there's loads of info on them.

01247 - Activated Charcoal Filters (evaps) System Solenoid Valve 1 (N80)
00635 - Oxygen (Lambda) Sensor Heating: Before CAT
01262 - Solenoid Valve for Boost Pressure Control (N75)
16486/P0102/000258 - Mass Air Flow Sensor (MAF/G70): Signal too Low
1658 Oxygen Sensor (O2S) 1, Bank 1/Heated Oxygen Sensor (HO2S) 1 (G39), Bank 1 - No Activity Detected



with these problems its no surprise you're cars not boosting. I can see at least 3 problems that would put it into limp home mode.

 

[Arrkon]

Ok so:

01247 - Activated Charcoal Filters (evaps) System Solenoid Valve 1 (N80)
00635 - Precat Lambda sensor heating
01262 - N75 short to ground
16486 - MAF signal too low
16518 - Precat lambda sensor signal

So looks as if you have a couple of faulty sensors (MAF/H02s/N80), However check fuse 34, it is the feed for a fair few sensors, cant remember off hand exactly what though (N80, Lambda heater i think)

 

[AudiA4B596]

Ok so:

01247 - Activated Charcoal Filters (evaps) System Solenoid Valve 1 (N80)
00635 - Precat Lambda sensor heating
01262 - N75 short to ground
16486 - MAF signal too low
16518 - Precat lambda sensor signal

So looks as if you have a couple of faulty sensors (MAF/H02s/N80)

But do you think all the sensors went wrong on the same day? Just seems like a coincidence, or could it have something to do with the computer/instrument panel (ECU - eeprom) ?

I will check the n75 and maf for any bad grounding tonight. I will also check that fuse, sounds promising!

Thank you for checking that out! Much appreciated!

 

[AudiA4B596]

Ok, so I checked for bad grounding, and I didn't find anything except an oil leak by the looks of it, and the fuse was fine which was disappointing, but nevermind. Going to try to copy my friends eeprom tomorrow as we have the exact same cars and i think mine got deleted, but so far no luck. Its just strange how everything went wrong at exactly the same time.

 

[Bradderz_1988]

Clear all them codes then drive it then read the codes again some could have been there for a while see whats actually present then go from there !!

 

[AudiA4B596]

Hey Bradderz, yes, I did that, it had nine codes before i cleared them and then drove it, had 5 afterwards and then cleared them again and drove it again and still the same 5 came back. See how the eeprom change goes tomorrow, im a little worried to be honest with fingers crossed!

Anyone have any idea where the oil leak may be coming from and why?

 

[Broken Byzan]

why are you changing eprom? I don't get it.

if you have zero boost it's mechanical not electrical. The worst an electrical fault can do is reduce it to actuator pressure of 5 or 6 psi. `As stated those faults are on the same feed so i suspect a break or short somewhere to cause them

 

[Arrkon]

Anyone have any idea where the oil leak may be coming from and why?

That isnt oil "per-se", its blow-by from the PCV system. That part is a fairly common failure on the 1.8t, it has a rubber O ring that perishes, and if I remember correctly, will leak boost around there too, seem to recall i had a leak around there.

But as per Mark's question, Why the eeprom?

 

[AudiA4B596]

Ok, so after some holiday time and a water over-heating problem, I've decided to try to find out what else is wrong with the car from before. I ran another vagcom test now that I have fixed the water problem. I had to change the cylinder-head gasket so had the engine in bits and cleaned everything up, took new oil and water, and new gaskets, belts and water-pump. So here is the results of the test now which were pretty similar to some months ago actually...




Here's some pictures of some of the work I've been doing to the engine itself and I was also hoping that the boost was leaking from the head gasket as well, as I was doing this anyway, but I had no luck.



From the codes it looks as if all the sensors/valves have grounded or aren't getting readings to he ecu.

As I said before, I haven't had hardly any boost for the past few months, between 1-2psi, so now I decided to do some tests.
First of all, I replaced all of the breather system as it was leaking blow-by. I also changed a broken orange oil-stick piece so I could get an accurate reading on the oil level.




First test, I disconnected the air filter and blocked it off, and connected an air compressor to the intake and set it to 15psi max, and run air through. I found two small leaks and fixed them with new hose-clips and they were gone when I repeated the test and no new leaks. I then had around 3 psi when driving.




I also disconnected the turbo from the exhaust and connected the air compressor to the wastegate to see if the wastegate was opening and closing, and it seemed to be functioning correctly. Nothing seems broken and the engine itself I know is very good.

Is there any other tests I could try?


Could the wiring loom have melted or got trapped rain water on an exposed wire that made it short out or could it be a faulty relay or fuse, as it is all the electronic components on the same line? Or could it be one that has failed and is making the others fail? I know the sensors and valves that are failing so I followed those wires back and they look ok to the eye and feel normal (e.g. not melted).

The car is booked into the Audi dealer, but here in Norway the dealer is outrageously expensive so I have about 10 days to find the problem myself or I'm probably going to get a huge bill.

Any ideas or advice would be much appreciated?

Thanks guys!

 

[Broken Byzan]

You checked all fuses? Ecu runs off several. Perhaps look for 12v at n80 for example or at 02plug

 

[AudiA4B596]

Hey Byzan,

I shall check the n80 for 12v tomorrow and see what we get...



Where would I find the o2plug? Is that the MAF? If so, how do I check that, it has more than 2 wires into it I think?



As for fuses, I've checked ALL the ones in the main fuse-box (Picture below) but I heard there are more fuses somewhere that are hidden? Is that true, and if so, are they worth a check? Would you happen to know where they might be?



Heres some other things I've been investigating and trying...

 

[Bradderz_1988]

02 plug is big brown connector under coolank tank !

when you checked the wastegate did you have any boost before checking it ?? As when i did exactly the same thing i only had 6psi before then started getting 12-14 psi for literally 2 gear changes then went back to 6 psi the penny valve wasnt sitting flush to the turbine housing !! Did you check this ??

try blocking off all the evap pipe on turbo intake pipe and manifold see if that helps in anyway !!

 

[aragorn]

check ALL the fuses relating to the engine management. The have silly vague names on the cover. Use a continuity tester and not your eyes.

As mentioned above, check for power at the various sensors that are giving fault codes, i bet you dont have any.

 

[AudiA4B596]

Hey guys,

Did some testing last night, started with the N80, and there was no power at all, I also checked the N75 and MAF (G70). Nothing. 0volts.



I wondered if there would be power to the ignition control module and if it was working so I borrowed one from a friend and tried his to see if it made any difference and all we found was that there was no difference unless it was unplugged, and then the car would not start, so I gather there is power through there which is running on the same line as the others that I have a problem with.



What does this conclude then? I have no power at any of these sensors/valves, but I do at the ignition control module because....?

I then moved on to locate the o2 plug, but I couldn't find a big brown connector under the coolant res...



Anyone know which one it would be here?

I've checked all the fuses in the normal fuse-box but are there fuses elsewhere I need to check?

When I checked my wastegate it sounded and felt like it was opening/closing good and flush but made no difference afterwards like bradderz had.

I shall also try to find time to block off the evap pipe and test that this weekend.

 

[Bradderz_1988]

Its the black one must be different on PFL !!

 

[AudiA4B596]

Its the black one must be different on PFL !!

Thanks bradderz! I'll check it out tomorrow.

 

[aragorn]

ICM is on a different fuseway to the other sensors IIRC? I'd need to check the wiring to be sure.

It could be the fuel pump relay, it has a few different contacts for different circuits.

I will try to look up the wiring tonight for you.

 

[AudiA4B596]

ICM is on a different fuseway to the other sensors IIRC? I'd need to check the wiring to be sure.

It could be the fuel pump relay, it has a few different contacts for different circuits.

I will try to look up the wiring tonight for you.

Thanks Aragorn, that would be awesome!

 

[aragorn]

OK.

N75, N80, G70 (MAF) and Lambda heater all share a power supply and fuse.

They're all powered from fuse S229 (29 in the box) which should be 20A.

Fuse 29 is then in turn supplied power from the fuel pump relay, however it shares a contact with the main fuel pump output, so i think that suggests the relay itself is ok?

I think you need to pull fuse 29, and see if 12v is present on the input to that fuse. If so, there must be a broken wire between that fuse, and the engine harness. I guess you'll have to trace the power through, it next appears on the 6 pin red multiplug in the ECU box, on pin 4, a red-green wire.

If theres no power at the fuse, then the fault has to exist between the fuel pump relay and the fuse box.

 

[AudiA4B596]

OK.

N75, N80, G70 (MAF) and Lambda heater all share a power supply and fuse.

They're all powered from fuse S229 (29 in the box) which should be 20A.

Fuse 29 is then in turn supplied power from the fuel pump relay, however it shares a contact with the main fuel pump output, so i think that suggests the relay itself is ok?

I think you need to pull fuse 29, and see if 12v is present on the input to that fuse. If so, there must be a broken wire between that fuse, and the engine harness. I guess you'll have to trace the power through, it next appears on the 6 pin red multiplug in the ECU box, on pin 4, a red-green wire.

If theres no power at the fuse, then the fault has to exist between the fuel pump relay and the fuse box.

Hey guys, I had some luck late last night, pretty sure i can fix it tonight but I'm at work now so I'll post a summary later tonight.... Thanks alot for all your help

 

[AudiA4B596]

Good news... I've finally... finally sorted it out.

I checked the black o2 plug the other night and realised no power there, so Bradderz was right about that.



This made me wonder if I had checked all the fuses properly as it had been about 3-4 months and I didn't clearly remember, so I wanted to double check the fuses again to make sure and I found that fuse 29 had in fact blown, which was weird as I didn't find this the first time. So I pulled out my unbelievably hard-to-understand norwegian handbook to see what fuse 29 was...



So, it says Motor and 20amps, I can understand that much, so that immediately got replaced and it was time for a new vag-com test... (At this point, I was kicking myself that I hadn't found this before, and also hoping that was all that was wrong...)

And, now I'm also kicking myself that I hadn't waited one more day for aragorn to reply, as he also got it right.

But, of course something had to make the fuse blow so I was then hoping that only one problem would come back...



And to my luck it did, just the N75. There was now power at the N80 and the G70 when I checked them and the car already felt like it was running better.

Now to figure out what was wrong with the N75...



I had a spare N75 on hand ready but first to see if there is any power there, which there wasn't.

Had to be the wiring then..

So I started striping back the black outer coating on the wiring to the N75, and when I got close to where the branches meet I now noticed the black part was melted underneath and had gone all the way through...



So I went in for the cut and striped that back so I could test if there was any power at the point at all...



Hurray! .. So I rewired the whole thing, soldiering and shrink wrapping, and I also made the wire longer than before so I could re-route it afterwards. Now to check if the plug has power and that I had done a good job..



Power!



New vag-com test...



And out for a drive.



In the picture I have around 6-7 psi boost, but in fact I was hitting 9-10 psi a lot of the time. It was a little difficult to get a good picture by myself whilst driving, but I'm well happy now!

Thanks a lot to everyone for their time to read and reply, you really helped me out a lot and guided me in the right direction and I really appreciate it. I really hope this thread might help out someone else in the future with the same or a similar problem.



I've also done some painting lately, getting some marmite responses but enjoy if you like lairy things...



Haha!

 

[aragorn]

Good stuff