MAF Sensor Voltage For 2003 1.8T

[THORDUDE]

Can somebody give me the voltage values of the MAF sensor for a 2003 Quattro 1.8T? What voltage and resistance per pin to check for when the car is at idle. I would like to see if harness is bad before forking out funds for new sensor. Could you also state the values with the plug connected and without? Thanks guys I was getting an average of 28 to 30 MPG and now it's around 16.

[PreciseD]

Is the black wire in #2 your probe? Do you have a MAF low voltage CEL?

[Don Supreme]

Perhaps VCDS logs would be an easier diagnostic tool for this task.

[THORDUDE]

Yes forgot to take it out before taking the picture...sorry ;)

[THORDUDE]

Yes but after having a car wash it came on so I want to rule out power to MAF before spending money I don't have.

[PreciseD]

Check for a vacuum leak first. Is the car running a little rough? If you get hard into the throttle in high RPMs is it misfiring?

[THORDUDE]

Thanks I'll find voltages

[old guy]

Thanks I'll find voltages

The voltage varies with conditions. That's how the MAF functions. you really need to monitor it while active. This should help: Clicky click

[THORDUDE]

What I meant to ask was what wire provides power (12 volts or above) to the MAF sensor? I understand that if fluctuates with load on other terminals but which pin number provides the power?

[old guy]

Clicky click

[THORDUDE]

Thank you so much old guy.

[THORDUDE]

Alright I'm getting 5 volts on pin 4 and 14.5 volts on pin 2, nothing on pin 3 or 5. Is the power going to wrong pin?

[old guy]

Sorry. Gave you some bad info. Terminal 2 should be battery voltage. With the engine started you should see battery voltage between terminal 2 and 3. Terminal 3 is a ground. A check between terminals 3 and 4 should produce 5 volts.

[THORDUDE]

Ok now I know the sensor is dunskied, would that take care of the following ECU error?

VCDS-Lite
Windows Based VAG/VAS Emulator
Version: Release 1.2
www.Ross-Tech.com
Workshop Code: 000 00000
Self-Diagnosis Log
Friday, 11 April 2014, 12:38:12:0
VIN Number: WAULC68E33A295419 License Plate:
Mileage: Repair Order:
Chassis Type: 8E - Audi A4 B6
Scan: 01,02,03,08,09,0F,11,15,16,17,18,36,37,45,46,55,56 ,57,65,67,69,75,76,77
-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Controller: 8E0 909 518 AF
Component: 1.8L R4/5VT G04 0003
Coding: 0016751
Shop #: WSC 63351
VCID: 749B5FD357A3
1 Fault Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 002 - Lower Limit Exceeded
Readiness: 0010 1101
-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01V-927-156.LBL
Controller: 8E0 927 156 P
Component: AG5 01V 1.8l5VT USA 0910
Coding: 0001002
Shop #: WSC 63351
VCID: 3B09B4EF3A7D
1 Fault Found:
18265 - Load Signal: Error Message from ECU
P1857 - 003 - Mechanical Failure
-------------------------------------------------------------------------------
Address 08: Auto HVAC Labels: 8E0-820-043.LBL
Controller: 8E0 820 043 K
Component: A4 Klimaautomat 1116
Coding: 00000
Shop #: WSC 63351
VCID: 29257EA7C0E1
1 Fault Found:
01841 - Potentiometer/Actuator for Temperature Flap; Left (G220)
30-10 - Open or Short to Plus - Intermittent
-------------------------------------------------------------------------------

Thanks for helping old guy.

[old guy]

If the MAF sensor is faulty then replacing it should cure both codes. Obviously the P0102 is connected to the MAF sensor. If the MAF sensor is reading low the ECM sometimes gives a P1857 load signal error since the load on the transmission will be greater than expected as calculated using the low reading from the MAF sensor. The ECM is pretty smart but it isn't programmed to interpolate how a low signal from one sensor will effect the function of other monitored operations.

Try clearing your codes, unplugging the MAF sensor and drive it a day or two. If your mileage gets better and the P1857 doesn't return then you will have pretty much confirmed a defective MAF sensor.

You could also try cleaning the sensor before replacing it to see if it helps.

Good luck!

[THORDUDE]

Called up the local used parts dealer and they had two in stock for $35, cleared both codes and running good. Until a new one came up. I'll get logs in a few.

[THORDUDE]

VCDS-Lite Windows Based VAG/VAS Emulator Version: Release 1.2 www.Ross-Tech.com
Workshop Code: 000 00000
Diagnostic Trouble Code Report Saturday, 12 April 2014, 19:05:20:0
VIN Number: License Plate: Mileage: Repair Order:
Control Module Part Number: 8E0 909 518 AF
Component and/or Version: 1.8L R4/5VT G04 0003
Software Coding: 0016751
Work Shop Code: WSC 63351 1 Fault Found:
16804 - Catalyst System; Bank 1: Efficiency Below Threshold P0420 - 002 - Lower Limit Exceeded

[old guy]

That one usually indicates a defective catalytic converter. How old is your cat? You can try resetting it and see how long the P0420 stays off. If it takes a week or more it is most likely the cat slowly breaking down. If it comes back immediately it could be the rear O2 sensor giving an erroneous reading.