Mass Air Flow (MAF) Sensor (G70) - Circuit Range/Performance Problem/Implausible Signal
Malfunction Indicator Lamp (MIL)(K83) active.
Loss of Power.
Air Leak(s) after Mass Air Flow (MAF) Sensor (G70).
Excessive restrictions in the Intake/Exhaust System.
Dirty air filter, clogged snow screen, clogged CAT.
Mass Air Flow (MAF) Sensor (G70) faulty,
Ground Spots corroded or Paint Residue.
Check/Replace all faulty Wiring/Connector(s).
Check Intake Air Filter.
Check Mass Air Flow (MAF) Sensor (G70).
Check Earth Points.
Read Measuring Value Blocks (MVB).
Mass air flow vs upper threshold model < 60 - 800 kg/h.
Lower threshold model < 0 - 400 kg/h.
Load calculation > 18%.
Fuel system < -17%.
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).
It is not uncommon for a TDI to set Implausible Signal Mass Air Flow Sensor (G70) faults when the engine performance is reduced due to a mechanical problem. These mechanical problems may include, but are not limited to:
Faulty electric fuel pump or Restricted fuel filter. See the Fuel Pump Basic Settings for PD, PPD, and CR TDI Engines page for Basic Settings tips after replacement.
Excessive restrictions in the intake/exhaust system.
Internal camshaft/valve/lifter problems.
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?:
A high voltage from the sensor is sent to Engine Control Module (ECM) under light load driving condition.
A low voltage from the sensor is sent to Engine Control Module (ECM).
The Mass Air Flow (MAF) Sensor (G70) 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.
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