Transmission in limp mode/MSF sensor

Old 05-09-2018, 09:56 PM
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Default Transmission in limp mode/MSF sensor

I've been having an issue with transmission on my 2003 Passat 1.8t constantly going into limp mode. The sunroof drains clogged so floor flooded into the TCU. I replaced TCU but it went into limp mode again. I discovered that fuse 36 didn't have power so tracked it to relay in slot 4 which turned out to be a no name no label relay that was the wrong one. I put in correct relay and power returned to many systems but I'm still left with code P0102 so I started looking at the Mass Air Flow sensor. I saws another post that said if the MAF wasnt working the system would go into limp mode. I read that if you unplug the MAF and the car continues to run it is defective but im not sure thats true. I checked plug for MAF and only seems to be power and very minimal at one of six slots. Wondering whats causing LIMP mode and if MAF gets power from anywhere else? Any suggestions would be greatly appreciated.
Old 05-10-2018, 07:48 AM
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First posts normally go in introductions else you could get a free fix and we never see you again!!!

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As posted in your first post.

VAG Error Code: 16486/000258

EOBD II Error Code: P0102

Fault Location:
Mass Air Flow (MAF) Sensor (G70) - Signal too Low/Lower Limit Exceeded

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Loss or Power.

Mass Air Flow (MAF) Sensor (G70) faulty.

Possible Solutions:
Check/Replace all faulty Wiring/Connector(s).
Read Measuring Value Blocks (MVB) 010.1.
Mass Air Flow (MAF) Sensor (G70) signal < 66 Ás.
Check/Replace Mass Air Flow (MAF) Sensor (G70).

Special Notes:
In MY 1995-2002 (?) in Europe at VW diesel cars Mass Air Flow (MAF) Sensor (G70) had the bad reputation of slowly losing his performance, causing loss of power. It's not a matter of defective or breaking down, but it is filthy/dirty (not easy to clean). You can check functionality by making a log in [01-engine], Measuring Value Blocks (MVB) 08, group 003 (3e gear, full throttle, from 1700-4000rpm).

Tech Notes:
Before replacing the mass air flow sensor, try replacing the air filter and cleaning the air flow sensor with low compress air or mass air flow sensor cleaner. Reset code and drive vehicle. If the code comes back, it may be necessary to replaced the mass air flow sensor.

When is the code detected?:
An excessively low voltage from the sensor is sent to Engine Control Module (ECM).

The Mass Air Flow (MAF) sensor is placed in the stream of intake air. It measures the intake flow rate by measuring a part of the entire intake flow. It consists of a hot film that is supplied with electric current from the Engine Control Module (ECM).

The temperature of the hot film is controlled by the Engine Control Module (ECM) a certain amount. The heat generated by the hot film is reduced as the intake air flows around it. The more air, the greater the heat loss. Therefore, the Engine Control Module (ECM) must supply more electric current to maintain the temperature of the hot film as air flow increases. The Engine Control Module (ECM) detects the air flow by means of this current change.
As taken from my new EOBD II Fault Codes Software
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