If your engine is not operating properly you should not assume that the turbocharger is at fault. In many cases a turbocharger is unnecessarily replaced when the fault is engine related. Consult the troubleshooting guidelines below, to see if your fault can be diagnosed.

This information should be used in conjunction with OEM diagnostic materials. 

Please refer to the safety instructions within our service manuals and installation guides when handling the turbocharger. Or use the Distributor Locator to contact your nearest Authorised Holset Distributor for servicing and repair options.

Troubleshooting Guidelines
Please click on the fault for further information.

Fault: Engine lacks power

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations.

Restricted air duct from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required.

Restricted intake manifold

Refer to engine manufacturer’s manual and remove restriction

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Restricted exhaust system

Remove restriction or replace damaged parts as required

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Gas leak at turbine inlet/exhaust manifold joint

Replace gasket or tighten fasteners as required

Fuel injection pump or fuel injectors incorrectly set

Refer to engine manufacturer’s manual and replace or adjust faulty components as required

Engine valve timing incorrect

Refer to engine manufacturer’s manual for correct settings and adjust as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset service repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Wastegate mechanism set incorrectly

Contact your nearest authorised Holset distributor for correct setting details

Fault: Poor Transient Response

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Restricted intake manifold

Refer to engine manufacturer’s manual and remove restriction

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Gas leak at turbine inlet/exhaust manifold joint

Replace gasket or tighten fasteners as required

Gas leak in ducting after turbine outlet

Refer to engine manufacturer’s manual and repair leak

Seized valve

Free valve/replace complete turbine housing sub-assembly

Wastegate mechanism set incorrectly

Contact your nearest authorised Holset distributor for correct setting details

Fault: Smoke

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Gas leak at turbine inlet/exhaust manifold joint

Replace gasket or tighten fasteners as required

Fuel injection pump or fuel injectors incorrectly set

Refer to engine manufacturer’s manual and replace or adjust faulty components as required

Wastegate mechanism set incorrectly

Contact your nearest authorised Holset distributor for correct setting details

Fault: Black exhaust smoke

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Restricted air duct from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Restricted intake manifold

Refer to engine manufacturer’s manual and remove restriction

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Restricted exhaust system

Remove restriction or replace damaged parts as required

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Gas leak at turbine inlet/exhaust manifold joint

Replace gasket or tighten fasteners as required

Fuel injection pump or fuel injectors incorrectly set

Refer to engine manufacturer’s manual and replace or adjust faulty components as required

Engine valve timing incorrect

Refer to engine manufacturer’s manual for correct settings and adjust as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Fault: Blue exhaust smoke

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as require

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Restricted turbocharger oil drain line

Remove restriction or replace damaged parts as required

Restricted engine crankcase breather

Refer to engine manufacturer’s manual, clear restriction

Turbocharger bearing housing sludged or coked

Change engine oil and oil filter, overhaul or replace turbocharger as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Fault: Noisy turbocharger

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Restricted air duct from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Restricted intake manifold

Refer to engine manufacturer’s manual and remove restriction

Air leak in feed from air cleaner to compressor

Replace seals, gaskets or tighten fasteners as required

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Exhaust manifold cracked, gaskets blown or missing

Refer to engine manufacturer’s manual and replace gaskets or damaged parts as required

Gas leak at turbine inlet/exhaust manifold joint

Replace gasket or tighten fasteners as required

Gas leak in ducting after turbine outlet

Refer to engine manufacturer’s manual and repair leak

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Failed diaphragm

Replace using correct Actuator Service Kit

Leaking hose

Replace hose and clips

Wastegate mechanism set incorrectly

Contact your nearest authorised Holset distributor for correct setting details

Fault: Cyclic sound from the turbocharger

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset service repair manual

Fault: Oil leak from compressor seal

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Restricted exhaust system

Remove restriction or replace damaged parts as required

Restricted turbocharger oil drain line

Remove restriction or replace damaged parts as required

Restricted engine crankcase breather

Refer to engine manufacturer’s manual, clear restriction

Turbocharger bearing housing sludged or coked

Change engine oil and oil filter, overhaul or replace turbocharger as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Fault: Oil leak from turbine seal

Restricted turbocharger oil drain line

Remove restriction or replace damaged parts as required

Restricted engine crankcase breather

Refer to engine manufacturer’s manual, clear restriction

Turbocharger bearing housing sludged or coked

Change engine oil and oil filter, overhaul or replace turbocharger as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Fault: High oil consumption

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Foreign object in exhaust manifold (from engine)

Refer to engine manufacturer’s manual and remove obstruction

Restricted turbocharger oil drain line

Remove restriction or replace damaged parts as required

Restricted engine crankcase breather

Refer to engine manufacturer’s manual, clear restriction

Turbocharger bearing housing sludged or coked

Change engine oil and oil filter, overhaul or replace turbocharger as required

Worn engine piston rings or liners

Refer to engine manufacturer’s manual and repair as required

Burnt valves and/or pistons

Refer to engine manufacturer’s manual and repair as required

Excessive dirt build-up on impeller and/or diffuser vanes

Clean in accordance with the appropriate Holset repair manual

Turbocharger damaged

Find and correct cause of failure, repair or replace turbocharger as necessary

Fault: Engine Running Hot

Dirty air cleaner

Clean or replace element according to manufacturer’s recommendations

Restricted compressor intake duct

Remove restriction or replace damaged parts as required

Restricted air duct from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Restricted intake manifold

Refer to engine manufacturer’s manual and remove restriction

Air leak in feed from compressor to intake manifold

Replace seals, gaskets or tighten fasteners as required

Air leak between intake manifold and engine

Refer to engine manufacturer’s manual and replace gaskets or tighten fasteners as required

Restricted exhaust system

Remove restriction or replace damaged parts as required

Failed diaphragm

Replace using correct Actuator Service Kit

Seized valve

Free valve/replace complete turbine housing sub-assembly

Leaking hose

Replace hose and clips

Wastegate mechanism set incorrectly

Contact your nearest authorised Holset distributor for correct setting details