Motronic OBD II Engine Management System

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WIRING DIAGRAM

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COMPONENT LOCATION VIEW

Motronic M5.2 Engine Management System: Component ID:

COMPONENT ID
592Fb Front heated oxygen sensor, cylinder bank 1
592Rb Rear heated oxygen sensor, cylinder bank 1
593F Front heated oxygen sensor, cylinder bank 2
593R Rear heated oxygen sensor, cylinder bank 2

4-Pin Connectors
H4-23 On a hose connected to the air pump, beside the air cleaner.
H4-24 On a bracket to the left of the rear exhaust manifold (black).
H4-25 On a bracket to the left of the rear exhaust manifold (grey).
H4-26 On a bracket to the left of the rear exhaust manifold (brown).

DESCRIPTION OF OPERATION
The Motronic M5.2 engine management system for OBDII differs only slightly from the Motronic M2.8.1 system.

Only the differences as compared to the regular system are described here.

M5.2 Control Module
Control module 587 monitors and controls the system.

Exhaust Emission Control, Lambda
The oxygen sensors, 593F for the front (cylinder bank 2) and 592F for the rear (cylinder bank 1) cylinder block, are mounted on the exhaust pipe. Their task is to provide the control module with data on the composition of the exhaust gases (oxygen content). Since the sensors continuously measure the oxygen content of the exhaust gases, the control module can adjust the fuel-air mixture and bring it as close as possible to lambda = 1.

Oxygen sensors are mounted after the catalytic converters (593R for cylinder bank 2 and 592Rb for cylinder bank 1) as a means of checking and diagnosing their operation.

They are also used to adjust the closed loop (Lambda) system to improve emission control additionally.

Oxygen sensor preheating element 271 is connected via fuse 28. Preheating is disconnected via control module 589.

FAULT DIAGNOSIS HINTS
The ISAT scan tool is used for fault diagnosis and obtaining readouts of diagnostic trouble codes.