22 · Diagnostics

Excessive fuel consumption

Make: Fiat
Model: Idea Factory Service Manual
Year: 2003–2012
Section: Consumption /leaks/ wear › Excessive fuel consumption

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Fault diagnosisExcessive fuel consumption

EXCESSIVE FUEL CONSUMPTION

1.3 JTD 16v

The engine appears to running smoothly, but the fuel consumption is higher than previously recorded during the life of the vehicle.

The consumption data in the vehicle technical documentation has been defined during the course of homologation tests in accordance with directive 93/116/CE.

These tests simulate an urban cycle and an 'average' extra-urban cycle and therefore may not be indicative as consumption depends very much on the style of driving.

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check the conditions: of the air filter of any leaks in the low or high pressure system obstructions in the exhaust system	Continue to Step 1	Filter element dirty or damaged	Replace the filter element Op. 1048A14
			Diesel leaks in the system	Restore system seal
			Exhaust system obstructed	Restore correct operation
1	CHECK WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the Examiner diagnostic equipment to the diagnostic connector and check the engine conntrol node: for faults in error mode; for plausibility of all parameters in parameter mode;	Continue to Step 2	Presence of error P0115	Continue to Step 2
			unreliable parameters	Continue following the instructions for the diagnostic equipment
			Presence of other errors in the control unit	Continue following the instructions for the diagnostic equipment
2	CHECK ENGINE TEMPERATURE SENSOR	All OK	Problems met	Operation
	Check the sensor signal is consistent with engine temperature	Continue to Step 3	Air temperature sensor fault	Replace sensor. Op. 1060G14
3	CHECK ACCELERATOR PEDAL POTENTIOMETER	All OK	Problems met	Operation
	Check the correct operation of the accelerator pedal potentiometer as described in the test See Test 1068AB Check operation of accelerator pedal potentiometer	Continue to Step 4	Potentiometer faulty	Replace potentiometer Op. 1068A20
4	HIGH PRESSURE CHECK	All OK	Problems met	Operation
	Connect the Examiner diagnostic equipment to the diagnostic socket. Check as described in the test See Test 1060D Check high pressure fuel circuitthat the diesel pressure parameter is correct. Check the operation of the rail high pressure sensor by carrying out the test See Test 1060GE Check on operation of diesel high pressure sensor Check the operation of the pressure regulator through active diagnosis.	Continue to Step 5	Sensor faulty	Replace sensor. Op. 1060G28
		Continue to Step 5	Pressure regulator faulty	Replace the pressure regulator Op. 1060E50
5	LOW PRESSURE CHECK	All OK	Problems met	Operation
	Check the fuel supply circuit, low pressure side: Carry out test See Test 1060B Low fuel pressure supply circuit check for low delivery pressure Carry out test See Test 1060A Low return fuel pressure circuit check for low return pressure	Continue to Step 6	Pressure not correct	Perform specific test for low fuel pressure supply system (filter, pipes, electric pump) to identify the faulty component
6	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

1.4 16v

The engine appears to running smoothly, but the fuel consumption is higher than previously recorded during the life of the vehicle.

The consumption data in the vehicle technical documentation has been defined during the course of homologation tests in accordance with directive 93/116/CE.

These tests simulate an urban cycle and an 'average' extra-urban cycle and therefore may not be indicative as consumption depends very much on the style of driving.

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Check the condition of the air filter Check the state of the spark plugs	Continue to Step 1	Filter element dirty or damaged	Replace the filter element Op. 1048A14
		Continue to Step 1	Spark plugs dirty or damaged	Replace the spark plugs Op. 5510D10
1	CHECK WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check that there are no faults in the engine management control unit	Continue to Step 2	An error is detected in the control unit	Continue following the instructions for the diagnostic equipment
		Continue to Step 2	Lack of dialogue with the control unit	Restore the connection between the engine management control unit and the diagnostic connector See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
2	CHECK ON INJECTORS	All OK	Problems met	Operation
	Using the diagnostic equipment (Examiner or other instruments) carry out the active diagnosis of the injectors	Continue to Step 3	Injector connections faulty	Restore the connection of the injectors with the control unit See E5030 PETROL ENGINE ELECTRONIC MANAGEMENT
		Continue to Step 3	Injectors faulty	Replace the injectors Op. 1056B70
3	CHECK ON FUEL PRESSURE	All OK	Problems met	Operation
	Check the fuel supply pressure Op. 0510C10	Continue to Step 4	Pressure not correct (too high a pressure is indicative of excessive consumption)	Replace the fuel pump assembly Op. 1040A70
4	CHECKING AIR CIRCUIT	All OK	Problems met	Operation
	Check the condition and seal of the air supply circuit	Continue to Step 5	Circuit component damaged	Replace the component
5	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis

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