Engine won't crank when trying to start
- Loose or oxidized battery terminal connections
- The battery is empty or defective
- Broken, loose or disconnected wiring in the starter circuit
- Defective starter relay or switch
- Faulty starter
- Broken starter gear teeth or flywheel ring gear (Section 2)
- Broken or disconnected engine ground strap
Engine cranks but won't start
- Empty fuel tank
- Low battery (motor rotates slowly)
- Loose or oxidized battery terminal connections
- Shunted or damaged ignition components - petrol models
- Broken, loose, or disconnected wiring in the ignition circuit - gasoline models
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Faulty preheating system - diesel models
- Faulty fuel injection system - models with a gasoline engine (Section 4)
- Faulty fuel cut-off valve - diesel models (Section 4)
- Air in the fuel system - diesel models (Section 4)
- Serious mechanical failure (e.g. camshaft drive) (Section 2)
Cold engine difficult to start
- Low battery
- Loose or oxidized battery terminal connections
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine (Section 1) /
- Faulty preheating system - diesel models
- Faulty fuel injection system - models with a gasoline engine (Section 4)
- Other malfunction in the ignition system - models with a gasoline engine
- Fast Idle Valve Improperly Adjusted - Diesel Models (Section 4)
- Low compression in the engine cylinders (Section 2)
Warm engine difficult to start
- Air filter element dirty or blocked
- Fuel Injection System Malfunction - Gasoline Engine Models (Section 4)
- Low compression in the engine cylinders (Section 2)
- Starter makes noise or rough engagement with flywheel ring
- Broken starter gear teeth or flywheel ring gear (Section 2)
- Loose or missing starter mounting bolts
- Worn or damaged internal starter components
Engine starts but immediately stalls
- Loose or defective ignition circuits - petrol models
- Vacuum leak in throttle body or intake manifold - petrol models (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
Unstable operation in idle mode
- Air filter element blocked
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Unequal or low compression in the engine cylinders (Section 2)
- Worn camshaft cams (Section 2)
- Toothed drive belt tensioned incorrectly (Section 2)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
- Faulty injector - diesel models (Section 4)
Ignition misfires at idle
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Faulty spark plug high voltage wiring - gasoline models
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
- Faulty injector - diesel models (Section 4)
- The distributor cap is cracked or burned from the inside - models with a gasoline engine
- Unequal or low compression in the engine cylinders (Section 2)
- Disconnected or damaged crankcase ventilation hoses (Section 4)
Misfires in all operating modes
- Clogged fuel filter element
- Faulty priming pump, or low supply pressure - models with a gasoline engine (Section 4)
- Drain hole in the fuel tank is blocked, or the flow area of the fuel lines has decreased (Section 4)
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Faulty spark plug high voltage wiring - gasoline models
- Faulty injector - diesel models (Section 4)
- The distributor cap is cracked or burned from the inside - models with a gasoline engine
- Faulty ignition coil - petrol models
- Unequal or low compression in the engine cylinders (Section 2)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
Engine fails when pressing gas pedal
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
- Faulty injector - diesel models (Section 4)
Engine stalls
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Clogged fuel filter
- Faulty priming pump, or low supply pressure - models with a gasoline engine (Section 4)
- Drain hole in the fuel tank is blocked, or the flow area of the fuel lines has decreased (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
- Faulty injector - diesel models (Section 4)
The engine does not develop full power
- Incorrectly installed or tensioned toothed drive belt (Section 2)
- Fuel filter clogged with dirt. Faulty priming pump, or low supply pressure - models with a gasoline engine (Section 4)
- Unequal or low compression in the engine cylinders (Section 2)
- Spark plugs worn, defective or incorrectly adjusted electrode gap - models with a gasoline engine
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
- Faulty injector - diesel models (Section 4)
- Injection timing incorrectly set - diesel models (Section 4)
- Wheel braking (Section 9)
- Clutch slip (Section 6)
The engine kicks back
- Incorrectly installed or tensioned toothed drive belt (Section 2)
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
The oil pressure warning light comes on when the engine is running
- Low oil level or wrong type of oil filled
- Faulty oil pressure sensor
- Worn crankshaft bearing shells and/or oil pump (Section 2)
- High engine operating temperature (Section 3)
- Defective oil pressure relief valve (Section 2)
- Clogged oil pump suction tube strainer (Section 2)
Engine running after shutdown
- Excessive soot in the engine (Section 2)
- High engine operating temperature (Section 3)
- Fuel Injection System Malfunction - Gasoline Engine Models (Section 4)
- Defective fuel cut-off valve - diesel models (Section 4)
Noise in the engine
- Preignition (detonation) or detonation under acceleration or under load
- Incorrect ignition timing / malfunction in the ignition system - models with a gasoline engine
- Spark plugs do not match engine type - petrol models
- Wrong grade of fuel
- Vacuum leak in throttle body, intake manifold, or associated hoses - Gasoline Models (Section 4)
- Excessive soot in the engine (Section 2)
- Clogged injector / malfunction in the fuel injection system - models with a gasoline engine (Section 4)
Whistling and hissing when the engine is running
- Leaky intake manifold gasket or throttle body - petrol models (Section 4)
- Leaking exhaust manifold gasket or exhaust pipe-to-manifold connection (Section 4)
- Vacuum hose leak (Sections 4 and 9)
- Cylinder head gasket damage (Section 2)
Tapping or rattling
- Worn valve train or camshaft (Section 2)
- Auxiliary components damaged (water pump, generator, etc.)
Low frequency knock
- Worn connecting rod bearings (regular intense tapping, possibly weakening under load) (Section 2)
- Worn main bearings (rattling or rattling, possibly worse under load) (Section 2)
- Piston knock (most noticeable when the engine is cold) (Section 2)
- Auxiliary components damaged (water pump, generator, etc.)