Mass air flow sensor reading 0.0

[todda7]

Hey!

When connecting with a VAG-COM trying to get the airflow, my MAF reads 0.0. I tried disconnecting and checking the MAF cable for faults, but it seemed fine. Took out the MAF, seems physically fine, but has no brand, the only markings on it is 101 101205, perhaps the previous owner replaced it?

What do you think? Bad MAF or something else?

Audi A4 2000 1.8T Quattro

Thanks!

EDIT: Solved with new MAF thanks to some helpful users.

[Wraith600]

You can log it with group 003. See if it is in fact actually not registering anything at all, which is odd because you would notice something like that. Why did you decide to look at your MAF in the first place?

[Believer]

Since his is an 00' they have a MAP sensor right? If the MAF is bad can't the motor continue on without missing a beat because of the MAP?

[Ducktool]

Definitely doesn't look like a Bosch PN so it's possible that it has been replaced. But I'm with wraith on this and need to know why you are investigating your maf in the first place. Are you having driveablility issues?

[todda7]

While driving and collecting data for chip-tuning the car, the tuner fired up VCDS and showed me real-time measurement of the air-intake, probably group 003, which was 0. He said the MAF was probably bad, but after looking around the forums, I can't find anyone with no reading, only a low one, and so I want to consider the possibility of something else being faulty before I replace the MAF.

Also, while disconnecting the MAF when idling, there was no audible difference, the car runs fine. I just got the car and so I don't know what fuel consumption etc. to expect, but if the ECU can't get a reading on the air intake, it's probably a lot higher than it needs to be.

[BaseDrifter]

Have you scanned for codes? You might have a P0102.

Here are some people with the same problem, though not much help for an answer: 1, 2, 3

Believer, only AWMs have a MAP sensor.

[todda7]

Yes, I scanned for codes and got one complaining something about Air Flow, I believe it was P0102 but I'm not 100 % sure. It also reported permanent under the fault code.

ANB motor btw. The motor runs fine (I cant tell the difference at idle) without the MAF cable connected.

[todda7]

Ordered a new MAF today. I believe the old one was a cheap generic one, hence the strange part number, so I'm betting it's broken. I ordered a cheap generic one too, but damn those OEM Bosch parts are over priced.

Thanks for help, will report after installing the new MAF.

[catbed]

Since his is an 00' they have a MAP sensor right? If the MAF is bad can't the motor continue on without missing a beat because of the MAP?

No, it does not work like that.

[Believer]

No, it does not work like that.

Wasn't sure. Thanks

[M-Hood]

Have you scanned for codes? You might have a P0102.

Here are some people with the same problem, though not much help for an answer: 1, 2, 3

Believer, only AWMs have a MAP sensor.

The ATW has a MAP sensor seeing it is also DBW, it happens to have a narrow band 02 sensor while the AWM has a wide band.

While driving and collecting data for chip-tuning the car, the tuner fired up VCDS and showed me real-time measurement of the air-intake, probably group 003, which was 0. He said the MAF was probably bad, but after looking around the forums, I can't find anyone with no reading, only a low one, and so I want to consider the possibility of something else being faulty before I replace the MAF.

Also, while disconnecting the MAF when idling, there was no audible difference, the car runs fine. I just got the car and so I don't know what fuel consumption etc. to expect, but if the ECU can't get a reading on the air intake, it's probably a lot higher than it needs to be.

No because the ECU mainly uses the 02 sensor at idle and part throttle to keep the AFR in check.

[todda7]

No because the ECU mainly uses the 02 sensor at idle and part throttle to keep the AFR in check.

Does the ECU use air flow to calculate AFR under load? Or is air flow measurement used to calculate boost pressure?

[BaseDrifter]

The ATW has a MAP sensor seeing it is also DBW, it happens to have a narrow band 02 sensor while the AWM has a wide band.

My mistake, could've sworn ATWs didn't have a MAP. Thanks for the correction.

[todda7]

Got me a VAG-cable!

Before clearing:
-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Controller: 4B0 906 018 AL
Component: 1.8L R4/5VT G 0002
Coding: 05201
Shop #: WSC 00000
VCID: 6BA944AF0A9D
3 Faults Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -
16502 - Engine Coolant Temperature Sensor (G62): Signal too High
P0118 - 35-10 - Please Register/Activate - Intermittent
17521 -Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - Please Register/Activate - Intermittent
Readiness: 0010 1101
-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8D0-959-655-AI8.LBL
Controller: 8D0 959 655 J
Component: Airbag Front+Seite 1001
Coding: 00104
Shop #: WSC 06335
VCID: 3D0DBAF72469
1 Fault Found:
65535 - Internal Control Module Memory Error
00-10 - - - Intermittent
-------------------------------------------------------------------------------
Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8D0 862 257 C
Component: ZV-Pumpe D12
Coding: 00001
Shop #: WSC 06335
VCID: 2D2D8AB7F409
5 Faults Found:
01367 - Central Locking Pump Run Time Exceeded (Likely Leak)
35-00 - -
01360 - Switch for Anti-Theft Alarm; Open
29-00 - Short to Ground
01365 - Lock/Unlock Switch; Interior
29-00 - Short to Ground
01389 - Tailgate Open Switch (F124)
29-00 - Short to Ground
00991 - Interior Lights
28-00 - Short to Plus
-------------------------------------------------------------------------------

After clearing and a 5 min drive:
-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Controller: 4B0 906 018 AL
Component: 1.8L R4/5VT G 0002
Coding: 05201
Shop #: WSC 00000
VCID: 6BA944AF0A9D
1 Fault Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-00 - -
Readiness: 0110 1101
-------------------------------------------------------------------------------
Address 15: Airbags Labels: 8D0-959-655-AI8.LBL
Controller: 8D0 959 655 J
Component: Airbag Front+Seite 1001
Coding: 00104
Shop #: WSC 06335
VCID: 3D0DBAF72469
1 Fault Found:
65535 - Internal Control Module Memory Error
00-10 - - - Intermittent
-------------------------------------------------------------------------------
Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8D0 862 257 C
Component: ZV-Pumpe D12
Coding: 00001
Shop #: WSC 06335
VCID: 2D2D8AB7F409
No fault code found.
-------------------------------------------------------------------------------

While driving, group 003 showed constant 0 gm/s air intake.
Should I be worried about the fault codes that disappeared?

Furthermore, what may cause the Airbag error?
EDIT: I reseated the yellow connection under the passenger seat, cleared the fault code, but no success. I guess I need a new module.

[catbed]

You need to check wiring to the MAF. If there is no change in sound when unplugging the MAF, then it means the car is already in limp mode. The code for MAF sensor signal too low points to a wiring problem as well.

Does the ECU use air flow to calculate AFR under load? Or is air flow measurement used to calculate boost pressure?

ECU uses MAF signal as main load input at all times. At part throttle and idle, the o2 sensors provide feedback because lambda = 1. When you got WOT, ECU goes open loop and uses MAF signal for fueling. Or in your case since the MAF is not giving a signal to the ECU, it switches to Alpha-n which is airflow over throttle plate. Boost has no effect on fueling.

Boost pressure desired is calculated using load.

[todda7]

Is there a connector on the other end of the MAF so I can beep it with a multimeter? I tried following the cable but I can't seem to find the other end . The cable seems physically fine, but I havent checked if there is actual connection. Thanks!

[catbed]

Is there a connector on the other end of the MAF so I can ping it with a multimeter? I tried following the cable but I can't seem to find the other end . The cable seems physically fine, but I havent checked if there is actual connection. Thanks!

Other end terminates at the ECU.

[walky_talky20]

The other end is the ECU. For the signal wire anyway. It also gets power and ground and such that come from fusebox and chassis, respectively.

[todda7]

I could not find the signal cable at the ECU-end, but Ground is OK, 5V is ~5V and 12V is ~14V.

[Wraith600]

16486 - Mass Air Flow Sensor (G70): Signal too Low - It can't see the MAF plugged in or it is bad. I would suggest buying the good BOSCH unit only because what I have read around here is that the knock off's don't last.

As for the other codes that didn't come back, your car may not have been driven long enough to generate them based on the readiness values in your log there.

0 = false 1 = ture
You can see your readiness under the engine module. I believe it takes 2 trips to basically cycle everything such as an O2 sensor like your original error had.

Start with the obvious one and go from there.

[todda7]

Got a cheap knock off MAF today. Installed, and voila! Almost like driving a new car afterwards. P0102 disappeared, and VCDS measured air flow. I also logged air intake on a trip, should I upload the log or assume it's ok? Idle: around 4 g/s, Max: 214 g/s

But the trip also got me these errors back:
16502 - Engine Coolant Temperature Sensor (G62): Signal too High
P0118 - 35-10 - - Intermittent
17521 -Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - Intermittent

The engine never surpasses 90*C. Should I be especially worried about these errors?

[Wraith600]

Yep that's how it should behave.

I believe the O2 is just a bad sensor, yet another Bosch part. Check group 032 I believe and see what your O2 is reading with Vagcom. Is it in spec after the car is warmed up?

I am not sure on the coolant sensor, I haven't had to trouble shoot that yet. If your temp sensor isn't reading properly then how do you know it's working properly. I always worry about every error because that's exactly the point, they are reporting something not function correctly. These cars work much better when the coolant is flowing properly as you want the engine to get a warmed up to spec. If your thermostat is working or sensor it may not allow the engine to warm up correctly, or it may, you just don't know.

There are tons of old threads about common issues with these cars, which seems to be a lot sometimes. Search them as I have learned most of what I know from them.

This has all the Vagcom codes and even suggested diagnostics or repairs attached to them.
http://wiki.ross-tech.com/wiki/index...ry:Fault_Codes

For exmaple,
http://wiki.ross-tech.com/wiki/index.php/17521/P1113
and
http://wiki.ross-tech.com/wiki/index.php/16502/P0118

You fuel economy should improve as well when addressing these other 2 codes, never mind the MAF you just replaced.

[todda7]

VCDS-Lite Version: Release 1.2
Friday, 14 March 2014, 15:49:28:0
Control Module Part Number: 4B0 906 018 AL
Component and/or Version: 1.8L R4/5VT G 0002
Software Coding: 05201
Work Shop Code: WSC 00000
VCID: 6BA944AF0A9D
4 Faults Found:
16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-00 - -
16524 - Oxygen (Lambda) Sensor B1 S2: No Activity
P0140 - 35-10 - - - Intermittent

O2 Log:
http://pastebin.com/QbKNiyRN

What are normal O2 values?

[catbed]

VCDS-Lite Version: Release 1.2
Friday, 14 March 2014, 15:49:28:0
Control Module Part Number: 4B0 906 018 AL
Component and/or Version: 1.8L R4/5VT G 0002
Software Coding: 05201
Work Shop Code: WSC 00000
VCID: 6BA944AF0A9D
4 Faults Found:
16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-00 - -
16524 - Oxygen (Lambda) Sensor B1 S2: No Activity
P0140 - 35-10 - - - Intermittent

O2 Log:
http://pastebin.com/QbKNiyRN

What are normal O2 values?

Sounds like you need a slew of new sensors? Do you still have your secondary air injection pump?

At cruise and idle lambda should be 1. At WOT it depends, anywhere from .85 - .7. But since you are a 2000, you have not way of telling the AFR at WOT unless you have a wideband gauge.

Your log seems to only show block 032, which are fuel trims. Which block did you log?

[todda7]

Sounds like you need a slew of new sensors? Do you still have your secondary air injection pump?

At cruise and idle lambda should be 1. At WOT it depends, anywhere from .85 - .7. But since you are a 2000, you have not way of telling the AFR at WOT unless you have a wideband gauge.

Your log seems to only show block 032, which are fuel trims. Which block did you log?

I haven't removed the SAI-pump at least, it's supposed to sit beneath the air-filter/MAF-box right? I just replaced a vacuum hose on the right side of the combi-valve, it was broken and probably have been for some time.

I logged group 032, which said lambda on both measurements. Arent those results from the O2 sensors?

Are all these sensors common faults, given the car has 110k miles?

[catbed]

I haven't removed the SAI-pump at least, it's supposed to sit beneath the air-filter/MAF-box right?

I logged group 032, which said lambda on both measurements. Arent those results from the O2 sensors?

Does the pump work? Your tune wants to see a flow from the pump which it doesn't see.

Block 032 is LTFTs, which are percent fuel correction. They are way off, but that's besides the point because of your sensor issues.

You need to correct those sensor problems first. New primary o2 and temp sensor, if the wiring is alright.

[todda7]

Is it possible that the post-cat O2 sensor (B1 S2) gives error because the pre-cat (B1 S1) isn't working?

[catbed]

Is it possible that the post-cat O2 sensor (B1 S2) gives error because the pre-cat (B1 S1) isn't working?

If there is no activity, it means the sensor is not there or it needed to be replaced last week.

[todda7]

But the error code is new What if the secondary air injection pump has failed, and the post cat sensor isnt't detecting because there isnt enough air going through?
Found a nice DIY video for fixing the SAI, I will do that first then check back on the O2 sensors. How is the general perception of non-OEM parts, like China made O2 sensors and SAI-pumps? Obviously they wont last as long, but perhaps it doesnt matter that much on a car thats already done 110k miles.

Thanks for help btw!

[catbed]

But the error code is new What if the secondary air injection pump has failed, and the post cat sensor isnt't detecting because there isnt enough air going through?
Found afor fixing the SAI, I will do that first then check back on the O2 sensors. How is the general perception of non-OEM parts, like China made O2 sensors and SAI-pumps? Obviously they wont last as long, but perhaps it doesnt matter that much on a car thats already done 110k miles.

Thanks for help btw!

It could be why the SAI is detecting improper flow. I'm not sure how the ECU detects SAI flow exactly since I have no desire to keep it. It can all be tuned out in the ECU easily.

Narrowband o2 sensors are cheap, and universal splice in ones are even cheaper. I would stick with bosch on o2 sensors. SAI pump is not necessary IMO

[todda7]

Great tip! OEM Bosch are 290 USD a piece here, but two of these soldered on would do the job?

I read somewhere that no SAI flow will destroy the cat?

[Wraith600]

The SAI pump you can do a test to see if it is cycling on or not. Yet another thing I had to replace as well. You need a registered version of VAGCOM to do the cycle test.

If I recall you go to engine, and basic setting on group 3. You cycle through various tests one of which cycles the SAI pump. Now even though you here it come on it may not product enough flow of air which can still trigger that error.

http://wiki.ross-tech.com/wiki/index...5/P0411/001041

I am chasing a lean condition that's not my MAF (just replaced it and logged fine) and randomly that again. In warmer weather I don't get it but when it gets to freezing temps it does so i am scratching my head a bit.

One thing I noticed in your LOG is how your O2 on the multi side is higher that the add side (add= idle, multi = while driving if I understand it correctly). So start with your o2's as suggested since you know for sure one is bad.

To do the SAI delete you need someone that can do ECU hex programming, it's not possible in VAGCOM. However, if you have emission testing like I do in Ontario, they connect it via OBD2 and it will fail if it fails the readiness test. So keep it if that's the case, which your going to hate the price if you have to replace it.

[catbed]

To do the SAI delete you need someone that can do ECU hex programming, it's not possible in VAGCOM. However, if you have emission testing like I do in Ontario, they connect it via OBD2 and it will fail if it fails the readiness test. So keep it if that's the case, which your going to hate the price if you have to replace it.

There is a way to delete SAI and pass emissions 100%.

[Wraith600]

The type that reads your readiness status with the code out? Please link or tell me how, I haven't seen it yet.

[todda7]

Would the car need to be chip-tuned again for best result, because the info the tuner collected probably was off due to bad MAF, O2, ECT and SAI?

[Wraith600]

I would say yes but I would need to know exactly how he "tuned" it. Was it sniffed (exhaust read?) and dyno'd?

The SAI won't be a factor as that only cycles on initial start up and once more after you come to a stop after driving for a few minutes.

MAF and O2 for sure, again depending on how it was tuned.

If it was just a drop in map then no, the map would be based on a properly working car.

[catbed]

The type that reads your readiness status with the code out? Please link or tell me how, I haven't seen it yet.

Passes emissions no problem. Still need to keep the pump relay and n112 or resistor the n112. K0mpressed posted it here I believe.

[todda7]

I would say yes but I would need to know exactly how he "tuned" it. Was it sniffed (exhaust read?) and dyno'd?

The SAI won't be a factor as that only cycles on initial start up and once more after you come to a stop after driving for a few minutes.

MAF and O2 for sure, again depending on how it was tuned.

If it was just a drop in map then no, the map would be based on a properly working car.

Neither sniffed nor dyno'd, he only logged something in VCDS and then tuned with some software (Kess or something).

Ordered two Bosch Universal Oxygen Sensors 15738, a 059919501A ECT sensor and a used (hopefully that doesn't matter?) Audi TT Dump valve 06A145710N, now the car ought to get in top shape.

[Wraith600]

Then I would said no re-tuning is needed.

As for the HEX coding for SAI, I read that post from Kompressed and I thought he was still waiting to see even with those modes done.

[catbed]

Then I would said no re-tuning is needed.

As for the HEX coding for SAI, I read that post from Kompressed and I thought he was still waiting to see even with those modes done.

My car passed NJ inspection today. No cat, no SAI pump or combi valve, resistored n112 and SAI pump relay coded out. Secondary o2 installed with no spacer. All readiness says passed in VCDS, but doesn't necessarily mean its actually passed.