Audi A4 VCDS Error Codes

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tecnic

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Hello

Hello Everyone. I have a 2003 Audi A4 with a 2.4 V6 petrol engine (BDV). I keep getting the MIL light on and even if I clear it, it will return within a few days of driving.

VCDS has captured the following errors which I would appreciate any assistance on.

Address 01: Engine Labels: Redir Fail!
Part No SW: 8E0 909 552 N HW: 8E0 909 052
Component: 2.4L V6/5V G01 0004
Coding: 0011581
Shop #: WSC 63351 000 00000
VCID: 39725A9373A6FDD69C9-515E

6 Faults Found:
17537 - Fuel Trim; Bank 2 (Mult)
P1129 - 002 - System too Rich - Intermittent
17535 - Fuel Trim; Bank 1 (Mult)
P1127 - 002 - System too Rich - Intermittent
16518 - Oxygen (Lambda) Sensor B1 S1
P0134 - 004 - No Activity - Intermittent
16538 - Oxygen (Lambda) Sensor B2 S1
P0154 - 004 - No Activity - Intermittent
16805 - Warm Up Catalyst; Bank 1
P0421 - 001 - Efficiency Below Threshold - Intermittent - MIL ON
16815 - Warm Up Catalyst; Bank 2
P0431 - 001 - Efficiency Below Threshold - Intermittent - MIL ON
Readiness: 0000 0000

The strange thing is, the car runs and drives fine. After a few days of driving locally, the MIL will come on. If I am driving on the motorway the car runs fine and sometimes the MIL turns off on it's own.

I cannot determine from these codes whether there is an issue with the Lambda sensor and if so which ones, or if there is an issue with fuel trim which I wonder could influence either reading.

Is there an advance setting within VCDS that can help me diagnose this issue further?

Any support would be appreciated, as I do not want to buy new o2 sensors if there is nothing wrong with them and they are reporting an error from something else that is wrong.

Many Thanks
Steve
 
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Jack@European_Parts

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Fuel PSI to high........... such as vacuum loss at regulation, etc.
Intake air leak or faulty MAF/MAP sensor........

Because it is multi, check the intake boot between TV and MAF for cracks, damage/installed improper.
 
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tecnic

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Hi

Thanks for your reply.

I hope I have fully understood your suggestions. I have replaced the air filter, checked the intake boot covers pre MAF and post MAF. I have just replace the MAF as well as all 6 spark plugs, timing belt change, water pump etc. I have also checked the crankcase pressure regulator and pipes which also seem fine.

I have just bought a replacement fuel filter to ensure there is no restriction on fuel, but apart from that I am at a loss.
 
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Jack@European_Parts

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What are the actual PSI and volume of fuel.........?

FPR function?

How is the N80 for Evap looking for sucking down vapors/stuck open causing enrichment during multi DTC report?
( Do a crimp off test to verify even though the readiness posted )

We have tugs for airplanes............I am sick of pushing cars in myself. Thinking of building a car tug.
 
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tecnic

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Hi Jack
Unfortunately I am not a mechanic, more of keen home DIY guy. Therefore, I do not fully understand everything you have mentioned here. Please bear with me as I am trying to learn as quickly as possible. I am still learning how to use VCDS too, so I am not sure where I can check these values of PSI and volume of fuel. Can you explain what FPR function, N80 and Evap is? I am not aware of how to do a crimp test either.
Is there some checks I can do with VCDS that would give more data that may help me get closer tot he problem?
Many Thanks
Steve
 
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Jack@European_Parts

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Hey Steve

No problem.

The N80 valve is the purge valve solenoid .......... which allows vapors from the fuel tank, to be reclaimed in the combustion chamber via the intake.
This valve can be observed by tracing the lines from intake, typically by the throttle valve back to a solenoid ( N80 ) then back to tank.

This is the rubber line you would crimp to see if the problem stopped while performing a readiness script in VCDS.
You should get a DTC for EVAP by crimping off.
In VCDS direct test ( 0x01-04-070 ) That means engine electronics button, then basic settings button, then input block # 070 GO/Next/ON.

You can use VCDS as a tester to identify the N80 in output tests for identifying a location.
In VCDS 0x01-03-GO/Next In VCDS this means Engine electronics button, then outputs button, then commence to test which states N80 pulse.
Go listen for click in engine bay........you just found N80.

Really what has to happen first is a repair manual for you to query.

https://erwin.audi.com/erwin/showVehicleSearch.do


Keep in mind the Multi DTC for rich fuel means we are getting to much fuel and it has to be getting there somehow.

FPR = Fuel PSI Regulator

The FPR controls overall fuel PSI on the rail of the injectors.
It is changed via vacuum or is sometimes contained in the fuel filter inline holding a static PSI.
There are two different types of FPR systems........one is single line fuel rail and one is two line with return to tank.

The difference between these regulators is, the one with the vacuum line will change the fuel PSI during atmospheric PSI change over, when the engine loses vacuum, the Regulator applies more PSI to the injectors during acceleration.
Hence enrichment. ( 2 fuel line )

If the regulation in the filter is faulty......... you can in rare cases get PSI which is off the charts, or have say....... a TSI 6 BAR regulator installed in a car which requires a 4 BAR regulation In error being the wrong part #.
( Single fuel feed line no return )

Either the fuel is being sucked from the tank direct via the N80 or rise of PSI or delivery of fuel is to much and needs to be corrected, providing false air or restriction of air is not present causing again less air and more fuel in the combustion process.
Hope this helps
 
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Jef

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Looks like the fuel pressure should be between 3.8 to 4.2 BAR for this vehicle.

From what I can tell, this car uses narrow band O2 sensors. It has been my experience that with these types of sensors, when fault codes get flagged, if the wiring harness is to factory design, then odds are the O2 sensors are in fact bad.

B1S1 (G39)
T4b/1 - fuse S234
T4b/2 - /5 of ECM
T4b/3 - /51 of ECM
T4b/4 - /70 of ECM

B1S2 (G108)
T4u/1 - fuse S234
T4u/2 - /4 of ECM
T4u/3 - /12 of ECM
T4u/4 - /13 of ECM

To that end, if you replace the O2 sensors, my suggestion is to get them from the dealer. We get a lot of feedback about parts that "came in a Bosch box", and most of the time it isn't positive feedback.
 
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Jack@European_Parts

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I would not recommend changing the oxygen sensors since they are both reading the same issue across both banks being sporadic.
It's not like the DTC's are short to ground or B+.
If in fact both bank OXS sensors were bad like Jef is saying, then you would have to still correct what caused the issue to heat them up that much to kill them.
It is my experience OXS sensors get changed way to often when not needed.
If given the opportunity to wake, and burn off contaminates...........they come right back.

What is stated about aftermarket OXS sensors in QUOTES is absolutely true, a real problem in the time of the clone wars.

Has any other work been done recently on this car?
How is the MAF and air cleaner/prescreen of air box........ any possible floating contaminates?
Does the car have any open campaigns or service actions for fuel pump or filter assembly?

I see a possible campaign for this vehicle for the fuel pump and it should be investigated for excessive wear problems.

The engine controller and all connection points to this car for the harness could be susceptible to water damage and it must be verified.

Please verify what FPR fuel system you have, either single line feed or with rail line return being two lines.
 
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tecnic

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Hi Jack

Many thanks for explaining further. I have carried out the n80 test and EVAP test.

Here is some results from VCDS that may or may not help me understand what is going on.


vcds, 01engine,15rediness, status is 00100001
all passed except oxygen sensor and catalytic converter

Then I tried crimping the line to EVAP test 070 and carried out the test. I did not get a DTC, but it did say passed on the test.

Output test N80 - I could hear air moving/suction.

I then looked at Readiness again and I got these results.

Readiness Status: 0110 1101
Exhaust Gas Recirculation: Passed
Oxygen Sensor Heating: Failed or Incomplete
Oxygen Sensor(s): Failed or Incomplete
Air Conditioning: Passed
Seconday Air Injection: Failed or Incomplete
Evaporative Emissions: Failed or Incomplete
Catalyst Heating: Passed
Catalytic Converter(s): Failed or Incomplete

Question. Is there a setting I can use in VCDS that would clear all values stored in the ECU for fuel, air , mixture settings etc, that perhaps would make the car run rough until it was driven for a while and learns the values all over again? I still find it weird that the engine seems to run fine, but I keep getting the engine warning light on after a couple of days.

You also mentioned if any work had been done recently. Well, this issue has been going on for a good few months now, but a couple of weeks ago, I carried out a full timing belt change with water pump - followed by all 6 spark plugs replaced, air filter, oil and oil filter, hydraulic fluid, coolant and now a new fuel filter. None of these have changed the way the car runs or the frequency of when the engine warning light come on.
Thanks for your support so far.
Many Thanks
Steve
 
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tecnic

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Hi Jack
I know you did not ask for this information, but I wonder if this may help. I check some other values in Engine 01...
block 32 =0,0,0,0
block 33-1 lambda goes from 3 to 8

block 33-3 lambda goes from 0 to 5 and back to 0
block 39 -1 mass flow 4.58 average
 
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Jack@European_Parts

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The fact that the EVAP test passed while being crimped is an indicator of a leak..........in VCDS 0x01-04-070
The reason that the readiness status didn't change for that indicator is, because it is a shared test within the controller with the LDP circuit.

LDP= Leak detection pump

This test in VCDS is 0x01-04-071 to pump the tank mechanically with air, using vacuum to operate pulsed by a solenoid.
If air leaks out there is a leak!
That air that pumps in is recycled via the N80 to the intake to burn off the vapors.

Understand better?
 
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Jack@European_Parts

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