Engine (Opel Omega A)

The engine does not start

• Battery connections are loose or corroded
• The battery is discharged or faulty
• The wiring in the starter circuit is faulty, loose or open
• The traction relay or starter switch is faulty
• Starter faulty
• Electric starter pinion or flywheel ring gear teeth are loose or broken
• Engine ground is damaged or disconnected

The engine turns over but does not start

• The fuel tank is empty
• The battery is discharged (the engine is turning slowly)
• Battery connections are loose or corroded
• Wet or damaged ignition system components - gasoline models
• Faulty, loose or open wiring in ignition circuit - gasoline models
• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Pre-heating system faulty - diesel models
• The throttle mechanism is incorrectly adjusted, worn out or sticking - petrol models with carburetor
• Defective fuel shut-off valve winding - petrol models with carburetor
• Damage to the fuel injection system - petrol models with fuel injection
• Fuel shut-off valve faulty - diesel models
• Air in Fuel System - Diesel Models
• Major mechanical failure (for example, camshaft drive)

The engine is difficult to start from a cold state

• The battery is discharged
• Battery connections are loose or corroded
• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Pre-heating system faulty - diesel models
• The throttle mechanism is incorrectly adjusted, worn out or sticking - petrol models with carburetor
• Damage to the fuel injection system - petrol models with fuel injection
• Other Ignition System Damage - Petrol Models
• Fast Idle Valve Not Adjusted Correctly - Diesel Models
• Low compression in engine cylinders

The engine is difficult to start when it is hot

• The air filter element is dirty or clogged
• The throttle mechanism is incorrectly adjusted, worn out or sticking - petrol models with carburetor
• Damage to the fuel injection system - petrol models with fuel injection
• Low compression in engine cylinders

The starter is noisy

• Electric starter pinion or flywheel ring gear teeth are loose or broken
• Starter mounting bolts are loose or missing
• The internal components of the starter are worn or damaged

The engine starts but immediately stalls

• Ignition circuit connectors are loose or faulty - gasoline models
• Vacuum leak in carburetor/throttle body or intake manifold - gasoline models
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection

Unstable operation in idle mode

• The air filter element is clogged
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Uneven or low compression in engine cylinders
• The camshaft lobes are worn out
• The drive chain is installed incorrectly
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection
• Injector faulty - diesel models

Misfires at idle speed

• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Defective spark plug high voltage wiring - petrol models
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol fuel injected models
• Injector faulty - diesel models
• Distributor cover cracked - petrol models (where applicable)
• Uneven or low compression in engine cylinders
• Disconnected or damaged crankcase ventilation hoses

Misfires across the entire speed range

• The fuel filter is clogged
• The fuel pump is faulty or the supply pressure is low
• The fuel tank opening or fuel lines are clogged
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Defective spark plug high voltage wiring - petrol models
• Injector faulty - diesel models
• Distributor cover cracked - petrol models (where applicable)
• Ignition coil faulty - petrol models
• Uneven or low compression in engine cylinders
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection

The engine accelerates with a delay

• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection
• Injector faulty - diesel models

The engine stalls

• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• The fuel filter is clogged
• The fuel pump is faulty or the supply pressure is low
• The fuel tank opening or fuel lines are clogged
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection
• Injector faulty - diesel models

Insufficient engine power

• The drive chain is installed incorrectly
• The fuel filter is clogged
• The fuel pump is faulty or the supply pressure is low
• Uneven or low compression in engine cylinders
• Spark plugs are worn, faulty, or installed with incorrect gap - petrol models
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection
• Injector faulty - diesel models
• Incorrect injection timing - diesel models
• Wheel braking
• Clutch slippage

The oil pressure warning light comes on when the engine is running

• Low oil level or wrong type of oil
• The oil pressure sensor is faulty
• Engine bearings and/or oil pump are worn out
• High engine operating temperature
• The oil pressure reducing valve is faulty
• The mesh filter of the oil pump inlet pipe is clogged

The engine continues to run after being turned off

• Excessive carbon deposits in the engine
• High engine operating temperature
• Defective fuel shut-off valve winding - petrol models with carburetor
• Damage to the fuel injection system - petrol models with fuel injection
• Fuel shut-off valve faulty - diesel models

Engine noises

Detonation or knocking noise during acceleration or when the vehicle is loaded

• Incorrect ignition timing/damage to ignition system - petrol models
• Wrong brand spark plugs installed - petrol models
• Wrong type of fuel was filled
• Vacuum leak in carburetor/throttle body, intake manifold or associated hoses - gasoline models
• Excessive carbon deposits in the engine
• Clogged jets or internal passages of the carburetor - gasoline models with a carburetor
• Clogged injector/damaged fuel injection system - petrol models with fuel injection

Whistling or wheezing noises

• Intake manifold or carburetor/throttle body gasket leaking - petrol models
• The exhaust manifold gasket or the connection between the tube and the manifold is leaking
• Vacuum hose leaks air
• The cylinder head gasket has blown

Light tapping or rattling

• Worn valve train or camshaft
• Auxiliary components are damaged (water pump, generator, etc.)

Loud or dull knocking sound

• Worn lower end connecting rod bearings (regular loud knocking noise, possibly decreasing when the vehicle is loaded)
• The main bearings are worn out (loud knocking noise, possibly increasing when the vehicle is loaded)
• The piston is damaged (most noticeable when the engine is not warmed up)
• Auxiliary components are damaged (water pump, generator, etc.)