Introduction
The engine control system on the diavel uses a sensor that measures air temperature. This sensor has a resistance of ntc type (negative temperature coefficient), that reduces its own value when the temperature increases. The air temperature sensor allows the engine control unit to modify the fuel-air mixture and ignition advance in relation to the atmospheric air temperature.
Components assembling position
The air temperature sensor is mounted on the right hand air intake (the image also shows the location of the connection).
Wiring diagram
Ccm engine control connection, s air temperature sensor. 1 Green/blue - g/b, 2 black/purple - bk/v.
In the event of fault
In the event of an air temperature sensor fault, the engine control unit implements a recovery value of 25C.
Fault codes generated and possible correlated faults
Fault codes generated by the engine control unit and displayed by the dds (intake air temperature sensor diagnosis):
Note
Check integrity of electric circuit - short-circuit to vdc = with dashboard on, using a voltmeter, a voltage is measured between the wire tested and ground.
Check integrity of electric circuit - short-circuit to ground = with the battery cables disconnected, using an ohmmeter, continuity is detected between the wire tested and ground.
Check integrity of electric circuit - open circuit = with the battery cables disconnected, using an ohmmeter, no continuity is detected between the two ends of the wire tested.
The dashboard service display shows the error "air temperature" and the eobd warning light activates.
Possible correlated faults: inadequate engine power, irregular idle speed (target idle speed is 1350 rpm with engine stabilised at operating temperature), the engine does not start easily. Check: -sensor resistance, which must be approximately 2 kohm at 25 C.
The air temperature value may be checked using the dds. Check that the value given is plausible.
If none of the aforementioned tests identify the problem and the air temperature sensor is in proper working order, replace the engine control unit.
Component replacement methods
No special measures are necessary in order to replace the air temperature sensor.
Removal of the cooling system hoses and unions
Loosen the clips (21) that secure the radiator/thermostat sleeve (40) and the
radiator/plug sleeve (24) to the water
radiators.
Loosen clips (25) and (43) that secure the breather pipe (26) to the
radiator/plug sleeve (24) and to the left radiator.
Loosen the clips (34) securi ...
Indicator cons. Avg - average fuel consumption
This function indicates the "average" fuel consumption.
The calculation is made considering the quantity of fuel used and
the km travelled since the last trip 1 reset. When trip 1 is reset,
the value is set to zero and the first available value is shown on
the display 10 seconds afte ...
Inspecting the final drive
To check the wear of the final drive, visually check the pinion (14) and
sprocket (17). If the teeth are found to worn as
shown in the figure (dotted line), the sprocket must be renewed.
To check the amount of wear on the chain (8), keep the chain taut and measure
16 links.
If the l ...