Smoke Diagnosis Charts

WARNING: This page is about a different variant/trim than selected.

The following charts include possible causes and corrections for excess or abnormal exhaust smoke. Small amounts of exhaust smoke (at certain times) are to be considered normal for a diesel powered engine.

EXCESSIVE BLACK SMOKE
POSSIBLE CAUSE	CORRECTION
Air filter dirty or plugged.	Check and replace the filter if necessary.
Air intake system restricted.	Check entire air intake system including all hoses and tubes for restrictions, collapsed parts or damage. Repair/replace as necessary.
Air Leak in Intake System.	Check entire air intake system including all hoses and tubes for collapse, cracks, loose clamps, or holes in rubber ducts. Also check intake manifold for loose mounting hardware.
Diagnostic Trouble Codes (DTC's) active or multiple, intermittent DTC's.	Refer to DTC INDEX .
Engine Control Module (ECM) has incorrect calibration.	Refer to DTC INDEX .
Exhaust system restriction is above specifications.	Check exhaust pipes for damage/restrictions. Repair as necessary.
Fuel grade is not correct or fuel quality is poor.	Temporarily change fuel brands and note condition. Change brand if necessary.
Fuel injection pump malfunctioning.	A DTC may have been set. If so. Refer to DTC INDEX .
Fuel injector malfunctioning.	A DTC may have been set. Perform "Injector Classification Programming" using scan tool. Also Return Fuel Quantity Test. Refer to DTC INDEX .
Fuel injector lower washer doubled or missing.	Remove and inspect injector washer.
Fuel return system restricted.	Check fuel return lines for restriction.
Intake manifold restricted.	Remove restriction.
Manifold Air Pressure (Boost) Sensor or sensor circuit malfunctioning.	A DTC should have been set. Refer to DTC INDEX .
Turbocharger air intake restriction.	Remove restriction.
Turbocharger damaged.	Refer to TURBOCHARGER, DIAGNOSIS AND TESTING .
Turbocharger has excess build up on compressor wheel or diffuser vanes.	Refer to TURBOCHARGER, DIAGNOSIS AND TESTING .
Turbocharger wheel clearance out of specification.	Refer to TURBOCHARGER, DIAGNOSIS AND TESTING .

EXCESSIVE WHITE SMOKE
POSSIBLE CAUSE	CORRECTION
Air in fuel supply: Possible leak in fuel supply side.	Inspect fuel system
Coolant leaking into combustion chamber.	Perform pressure test of cooling system.
Diagnostic Trouble Codes (DTC's) active or multiple, intermittent DTC's.	Refer to DTC INDEX .
In very cold ambient temperatures, engine block heater is malfunctioning (if equipped).	Refer to HEATER, ENGINE BLOCK, DIAGNOSIS AND TESTING .
Engine coolant temperature sensor malfunctioning.	A DTC should have been set. Refer to DTC INDEX . Also check thermostat operation.
Engine Control Module (ECM) has incorrect calibration.	A DTC should have been set. Refer to DTC INDEX .
Fuel filter plugged.	Refer to DIAGNOSIS AND TESTING .
Fuel grade not correct or fuel quality is poor.	Temporarily change fuel brands and note condition. Change brand if necessary.
Fuel injector malfunctioning.	A DTC should have been set. Perform "Injector Identification Programming" or "Cylinder Cutout Test" using scan tool to isolate individual cylinders. Also, refer to DTC INDEX .
Fuel injector hold-down(s) loose.	Replace the copper washer(s) (shim) and tighten to specifications.
Fuel injector protrusion not correct.	Check washer (shim) at bottom of fuel injector for correct thickness.
Fuel injection pump malfunctioning.	A DTC should have been set. Refer to DTC INDEX .
Fuel supply side restriction.	Refer to DIAGNOSIS AND TESTING for fuel system testing.
Intake manifold air temperature sensor malfunctioning.	A DTC should have been set. Refer to DTC INDEX .
Intake manifold heater circuit not functioning correctly in cold weather.	A DTC should have been set. Refer to DTC INDEX . Also check heater elements for correct operation.
Intake manifold heater elements not functioning correctly in cold weather.	A DTC should have been set if heater elements are malfunctioning. Refer to DTC INDEX .
Internal engine damage (scuffed cylinder).	Analyze engine oil and inspect oil filter to locate area of probable damage.
Restriction in fuel supply side of fuel system.	Refer to DIAGNOSIS AND TESTING for fuel system testing.

EXCESSIVE BLUE SMOKE
POSSIBLE CAUSE	CORRECTION
Dirty air cleaner or restricted turbocharger intake duct.	Check Air Cleaner Housing for debris and replace filter as necessary
Air leak in boost system between turbocharger compressor outlet and intake manifold.	Service charge air system.
Obstruction in exhaust manifold.	Remove exhaust manifold and inspect for blockage.
Restricted turbocharger drain tube.	Remove turbocharger drain tube and remove obstruction.
Crankcase ventilation system plugged.	Inspect oil separator system for function and clear drain back hole in cylinder head cover/intake manifold
Valve seals are worn, brittle, or improperly installed.	Replace valve stem oil seals
Valve stems or guides are worn.	Remove valves and inspect valves and guides.
Broken or Improperly installed piston rings.	Tear down engine and inspect piston rings.
Excessive piston ring end gap.	Remove pistons and measure piston ring end gap.
Excessive cylinder liner wear and taper.	Remove pistons and measure cylinder liner wear and taper.
Cylinder damage.	Remove pistons and inspect cylinder liner for cracks or porosity. Repair with new cylinder liner if necessary.
Piston damage.	Remove pistons and inspect for cracks, holes. Measure piston for out-of-round and taper.
Turbocharger failure.	Refer to TURBOCHARGER, DIAGNOSIS AND TESTING .