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Discussion Starter #1
Hi, I have a 03 beetle. Last weekend I got engine light (P0103, P0113) and EPC light. I sent my car for checking, replaced MAF connector.

However, the lights is still there. My mechanic told me I do not need to change the MAF sensor and it may be the MAF connector wiring issue. There's no 12V from pin 2. I also have check fuse 43, it's good, fuse 163, it's good too. And I searched on web and found maybe the relay J17 is the reason. (I have not checked J17 yet.)

I want to repair the car and let it run well, I love this car. Could anybody give me more suggestion? Thanks!
 

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http://wiki.ross-tech.com/wiki/index.php/16487/P0103/000259

16497/P0113/000275 - Ross-Tech Wiki

The maf sensor, on the 2.0L engine; integrates the maf and intake temp sensor; into the whole maf assembly. Because, of the two trouble codes, it makes me wonder if the maf is bad or the wires/plug are defective. Ideally, it would be nice; to read "live data" on a scan tool and see, what the maf and intake temps are. If you there aren't any readings at all; then, that would confirm, the problem and you would need to check the wires and maf/iat assembly, to see if it is bad. Wiggling the wires, as the car is running and you are reading the readings of the sensor, would be a good technique, to confirm the wiring is good/bad or have a loose connection, as well.

If you need a new plug or replace some of the terminal ends; you can purchase these online with plug/pigtail combo or buy individual parts at your local VW dealer. Damages plugs/terminal ends on the MAF connector, are VERY common and I had to do it on my new beetle. My connector locking tab was broken and the red inner terminal locking portion; cracked and fell apart. I chose, to get a genuine vw part and the new plug didn't cost too much.

Mass Air Flow Sensor 5 Pin Connector Plug Volkswagen part # 1J0973775A (you can confirm the part #; by looking at your old plug, it will have the part number imprinted on it.)

https://duckduckgo.com/?q=vw+maf+connector+replacement&atb=v140-1_p&ia=products

Here is a page, discussing; how to test the maf with a multimeter. (NOTE: there are 4 and 5 wire type mafs):

https://easyautodiagnostics.com/vw/1.8L/index-of-articles-1

I don't know, what type of tools you have access to but most auto parts stores, will loan you a obd II scan tool, which should be able to display the maf and intake air temps.

Here is a link; to the factory vw service manual and it shows, testing procedures: (there are more then one page; so, keep advancing to the next page, you might print these out, to refer to as you work on the problem:

https://workshop-manuals.com/volkswagen/new_beetle/l4-2.0l_(azg)/powertrain_management/fuel_delivery_and_air_induction/air_flow_meter/sensor/component_information/testing_and_inspection/with_manufacturers_scan_tool/page_3298/

So, do some testing, wiggle the wires/plug, while the engine is running, see if the maf readings are affected by the wiggling and let us know the results of your troubleshooting, then, we can go from there. Thanks! :)
 

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Discussion Starter #4
I use my BlueDriver code read and get the following data:

a) Speed: 0km/h / Engine RPM:793 / Intake Air Temp -40C / Mass Air Flow Rate: 14.25 g/s
b) Speed: 0km/h / Engine RPM:2006 / Intake Air Temp -40C / Mass Air Flow Rate: 232.50 g/s

I was told by my mechanic that pin2 of MAF connector is 0V. So he didn't think my MAF sensor should be replaced.

Any suggestion to my lovely NB?
 

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So, it looks like it is jumping up/down on the maf readings and the intake temp @ -40 is definitely off. I have seen this jumping reading symptom before, on defective mafs or you have a wiring problem, although, i tend to think it would be the maf. This is just my opinion; i could be wrong.
 

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If you decide to replace the mass airflow sensor; stick with a genuine OEM quality Bosch sensor. Do not buy cheap aftermarket mass airflow sensors; they do not work correctly and fail making the car room horrible. The original Bosch MAF sensor, uses a thin film style sensor to get a accirate reading; the aftermarket ones ise a poor quality sensor rtype that does not read the air flow correctly/accurately. Bosch sensors are the correct original type that came installed at the vw factory and are quality sensors that we have seen to work as they should. You can look up the Bosch part number; for the correct sensor for your particular car, on their website here:
 

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Discussion Starter #9
Thank you for your opnion. I just think there's no power on Pin 2 of MAF connector, so a new MAF can not make my car better. Is it ?
 

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Discussion Starter #10
And I also checked the wire of MAF connector under thr engine hook. It looks good . However it jist looks good. I do not know is there any fuse or relay that's provide the power to it. I did not found the circuit diagram.
 

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I suggest, you print out the pages; that I linked to above and following the factory vw testing procedures, making sure, you follow the terminal identification shown in the images.

testing is as follows:

Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor -G70-

with Intake Air Temperature (IAT) Sensor -G42- (arrow).

Vehicles with engine code BDC-Disconnect 5-pin connector from Mass Air Flow (MAF) Sensor -G70- with Intake Air Temperature (IAT) Sensor -G42- (arrow).

Continuation for all vehicles

-Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.

-Start engine, and let run at idle.

Specified value: 11.0 to 15.0 V

-Switch ignition off.

If there is no voltage:

-Check wire between 5-pin connector terminal 2 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.

Wire resistance: max. 1.5 Ohms

If voltage supply and wires are OK

 

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Discussion Starter #14
Tonight, I have done the test:

1. Unplug the 5 pin MAF connector from MAF sensor;
2. Check the voltage of the car battery with multimeter, it's 12V;
3. Check 5 pin connect, only 0.01~0.04 v between pin 2 and 3; and no voltage between pin 4 and 3;
4. Check all the fuses, even the fuses on the relay panel, that's fine.

So, I think I should check the MAF wiring or relay? Or ECU?

Any idea? Thanks.
 

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Was the car running, according to; the above recommended testing procedure/step?

-Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.

-Start engine, and let run at idle.

Specified value: 11.0 to 15.0 V
 

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Discussion Starter #16
Yes, the engine is running at idle.
the value between terminal 2 and battery - is 0V.
the value between terminal 2 and terminal 3 is only 0.01~0.04V.
 

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Well, assuming, you did the test correctly; it would seem, you need to check the relay and wiring, until you find power, from the ecu? A bad relay or a continuity test to the ecu plug and ultimately, the ecu, itself, might be a problem?
 

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Discussion Starter #19
As a result of research on internet, J17 (relay type 409) maybe the reason of my car. Is it necessary for me to check this relay?
 
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