Motronic ME 7
Charge Air Pressure Sensor G31
(1.8Turbo, M7.5.1)
In ME 7, the sensor is mounted in the intake tract
between the charge air cooler and theThrottle Valve
Control Module J338.
Operation
Charge Air Pressure sensor G31 is a piezo-electro
sensor. Operation is via a 5V reference from the ECM,
with varying resistance to indicate manifold absolute
pressure. Atmospheric pressure provides a signal of
approximately 2.5V. Range of operation for the ECM
to recognize a plausible signal is 0.14V - 4.88V.
Substitute Function
If the Charge Air Pressure Sensor G31 fails, charge
pressure is controlled by a calculation map based on
engine speed and load. Power output is also reduced.
On Board Diagnostic
The ECM recognizes short circuit to Battery +, short
circuit to Ground, as well as implausible signals. The
ECM cross checks the Charge Air Pressure Sensor
G31 against the BARO Sensor F96. If a difference of
200 mbar is seen, a code for implausible signal is set.
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