Engine does not rotate when trying to start
- Loose or broken battery terminal connections due to corrosion («Weekly checks»).
- The battery is empty or defective (chapter 5).
- Broken, disconnected, or poorly connected start circuit wiring (chapter 5).
- Faulty starter (chapter 5).
- Worn or broken starter gear teeth or flywheel/faceplate ring gear (chapters 2 and 5).
- Broken or disconnected engine ground bus (chapter 5 or 12).
Engine turns over but does not start
- Empty fuel tank.
- The battery is empty (motor rotates slowly) (chapter 5).
- Loose or broken battery terminal connections due to corrosion («Weekly checks»).
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Pre/Postheater Malfunction - Diesel Engines (chapter 5).
- Faulty engine management system (chapter 4).
- Air in the fuel system - diesel engines (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Low compression in the cylinders (chapter 2).
- Serious mechanical failure (for example, a malfunction of the gas distribution mechanism) (chapter 2).
Starting a cold engine is difficult
- The battery is empty (chapter 5).
- Loose or broken battery terminal connections due to corrosion («Weekly checks»).
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Pre/Postheater Malfunction - Diesel Engines (chapter 5).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Low compression in the cylinders (chapter 2).
Starting a warm engine is difficult
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Low compression in the cylinders (chapter 2).
Increased noise or knocking when the starter is running
- Worn or broken starter gear or flywheel ring gear teeth (chapters 2 and 5).
- Starter mounting bolts loose or missing (chapter 5).
- Faulty starter (chapter 5).
Engine starts but immediately stalls
- Broken vacuum in the throttle body or in the intake manifold - gasoline engines (chapter 4).
- Faulty engine management system (chapter 4).
- Air in the Fuel System - Diesel Engines (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
Engine idling unevenly
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines.
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Faulty engine management system (chapter 4).
- Air in the Fuel System - Diesel Engines (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Inequality or low compression value in the cylinders (chapter 2).
- Camshaft lobes wear (chapter 2).
- Incorrect installation of the timing belt (chapter 2).
Misfires while the engine is idling
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Inequality or low compression value in the cylinders (chapter 2).
- Disconnected, Leaking or Missing Crankcase Ventilation Hoses - Diesel Engines (chapter 4)
Misfires during engine operation over the entire speed range
- Clogged fuel filter (Chapter 1).
- Faulty fuel pump - gasoline engines (chapter 4).
- Fuel tank vent valve clogged or fuel lines obstructed (chapter 4).
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Throttle Body/Intake Manifold Vacuum Broken - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Faulty ignition coil - gasoline engines (chapter 5).
- Inequality or low compression value in the cylinders (chapter 2).
Engine runs erratically when accelerating
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
Engine stalls
- Clogged fuel filter (Chapter 1).
- Faulty fuel pump - gasoline engines (chapter 4).
- Fuel tank vent valve clogged or fuel lines obstructed (chapter 4).
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
Insufficient engine power
- Incorrect installation of the timing belt (chapter 2).
- Clogged fuel filter (Chapter 1).
- Faulty fuel pump - gasoline engines (chapter 4).
- Inequality or low compression value in the cylinders (chapter 2).
- Worn, malfunctioning, or misadjusted spark plug spark plugs - gasoline engines (Chapter 1).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
- Sticky brakes (chapter 1 and 9).
- Clutch slip (chapter 6).
Popping in the engine
- Incorrect installation of the timing belt (chapter 2).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Faulty engine management system (chapter 4).
The oil pressure warning lamp lights up when the engine is running
- Low oil level or wrong brand of oil («Weekly checks»),
- Faulty oil pressure sensor (chapter 5).
- Engine bearing wear and (or) oil pump (chapter 2).
- High engine operating temperature (chapter 3).
- Faulty oil safety valve (chapter 2).
- Clogged oil filter (chapter 2).
The engine continues to run after the ignition is turned off
- Increased carbon deposits in combustion chambers (chapter 2).
- High engine operating temperature (chapter 3).
- Faulty engine management system (chapter 4).
- High Pressure Fuel System Malfunction - Diesel Engines (chapter 4).
Noises in the engine
Preignition (detonation) or knocking sound when accelerating or under load
- Faulty engine management system (chapter 4).
- Incorrect spark plug type selected - gasoline engines (Chapter 1).
- Fuel of the wrong brand - gasoline engines (chapter 4).
- Broken Throttle Body/Intake Manifold Vacuum - Gasoline Engines (chapter 4).
- Increased carbon deposits in combustion chambers (chapter 2).
Whistling or sniffling sounds
- Leakage at the intake manifold or throttle body gasket - gasoline engines (chapter 4).
- Vacuum hose leak (chapter 9).
- Broken cylinder head gasket (chapter 2).
Light tapping or rattling noises
- Valve train or camshaft wear (chapter 2).
- Auxiliary equipment failure (coolant pump, generator, etc.) (chapters 3, 5 etc.).
Bumps or thuds
- Wear of the bearings of the lower head of the connecting rod (regular hard hitting that can weaken under load) (chapter 2).
- Wear of main bearings (rumbling and thumping, which may increase under load) (chapter 2).
- Piston knock (especially noticeable when the engine is cold; caused by piston/cylinder wall wear) (chapter 2).
- Auxiliary equipment failure (coolant pump, generator, etc.) (chapters 3, 5 etc.).