22 · Diagnostics

Co emissions low, nox emissions high

Make: Fiat
Model: Croma Factory Service Manual
Year: 2005–2010
Section: Emissions › Co emissions low, nox emissions high

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Fault diagnosisCo emissions low, nox emissions high

CO EMISSIONS LOW, NOX EMISSIONS HIGH

1.8, 2.2

The CO percentage measured is very low, whilst the NOX percentage is higher than recommended.

1	CHECK USING DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
		Results of the tests
	Connect the diagnostic test equipment (Examiner or other instruments) to the tester input. Check that there are no faults in the engine management control unit	Move on to Step 2	"Fuel system" error detected	See table Z50 ERRORE TITOLO MISCELA
			"Misfire" error detected	See table Z53 ERRORE MANCATE ACCENSIONI
			"Catalyzer" error detected	See table Z55 ERRORE CATALIZZATORE
			"Upstream Lambda sensor" error detected	See table Z56 ERRORE SEGNALE LAMBDA A MONTE
			"Downstream Lambda sensor" error detected	See table Z58 ERRORE SEGNALE LAMBDA A VALLE
			Another error detected in the control unit	Continue following the instructions for the diagnostic equipment
			No communication with the control unit	Restore the connection between the engine management control unit and the diagnostic connector See See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT
2	ACTIVE DIAGNOSIS WITH DIAGNOSTIC EQUIPMENT	All OK	Problems encountered	Operation
	Connect the diagnostic equipment (Examiner or other instruments) and carry out the active diagnosis for the injectors.	Move on to Step 3	Connections faulty	Restore connection for injectors and solenoid valve with control unit See See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT
		Move on to Step 3	Injector fault	Replace the injector Op. Op. 1056B70 INJECTOR (ONE) - R + R WITH FUEL MANIFOLD PIPE REMOVED - INCLUDES SEAL REPLACEMNT
3	UPSTREAM LAMBDA SENSOR CHECK	All OK	Problems encountered	Operation
	Check that the upstream Lambda sensor is working properly See Test See Test 1080BA CHECK ON OPERATION OF UPSTREAM LAMBDA SENSOR	Move on to Step 4	Left Lambda sensor defective	Replace the left Lambda sensor Op. Op. 1080B94 FRONT LAMBDA SENSOR TO WITH CATALYTIC CONVERTER - R.R
		Move on to Step 4	Right Lambda sensor defective	Replace the right Lambda sensor Op. Op. 1080B94 FRONT LAMBDA SENSOR TO WITH CATALYTIC CONVERTER - R.R
4	DOWNSTREAM LAMBDA SENSOR CHECK	All OK	Problems encountered	Operation
	Check that the downstream Lambda sensor is working properly See Test See Test 1080BD CHECK ON OPERATION OF DOWNSTREAM LAMBDA SENSOR	Move on to Step 5	Lambda sensor defective	Replace the Lambda sensor Op. 1080B95 REAR LAMBDA SENSOR TO CATALYTIC CONVERTER - R.R
5	AIR CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check the condition of the air supply circuit	Move on to Step 6	Circuit component damaged	Replace the component involved
6	BLOW-BY CIRCUIT CHECK	All OK	Problems encountered	Operation
	Check the condition of the blow-by gas intake circuit: in particular, check for obstructions in the separator or pipes.	Move on to Step 7	Circuit faulty	Restore circuit to working order
		Move on to Step 7	Fault in the separator	Replace the separator
7	FUEL PRESSURE CHECK	All OK	Problems encountered	Operation
	Check the fuel supply pressure Op. Op. 0510C10 FUEL SYSTEM - CHECK DELIVERY PRESSURE	Move on to Step 8	Pressure not correct	Replace the fuel pump
8	CHECK CORRECT OPERATION	All OK	Problems encountered	Operation
	Check that the fault is no longer present		Fault persists	Search for the fault starting from another symptom

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Parts & tools for this job For 2005 Fiat Croma

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