Engine fault finding (Peugeot 106)

Engine fails to rotate when attempting to start

• Battery terminal connections loose or corroded ("Weekly Checks").
• Battery discharged or faulty (Chapter 5A).
• Broken, loose or disconnected wiring in the starting circuit (Chapter 5A).
• Defective starter solenoid or switch (Chapter 5A).
• Defective starter motor (Chapter 5A).
• Starter pinion or flywheel ring gear teeth loose or broken (Chapters 2A and 5A).
• Engine earth strap broken or disconnected (Chapter 5A).

Engine rotates, but will not start

• Fuel tank empty.
• Battery discharged (engine rotates slowly) (Chapter 5A).
• Battery terminal connections loose or corroded ("Weekly Checks").
• Ignition components damp or damaged - petrol models (Chapters 1A and 5B).
• Broken, loose or disconnected wiring in the ignition circuit - petrol models (Chapters 1A and 5B).
• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Preheating system faulty - diesel models (Chapter 5C).
• Choke mechanism incorrectly adjusted, worn or sticking - carburettor petrol models (Chapter 4A).
• Faulty fuel cut-off solenoid - carburettor petrol models (Chapter 4A).
• Fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Stop solenoid faulty - diesel models (Chapter 4D).
• Air in fuel system - diesel models (Chapter 4D).
• Major mechanical failure (eg camshaft drive) (Chapter 2A, 2B or 2C).

Engine difficult to start when cold

• Battery discharged (Chapter 5A).
• Battery terminal connections loose or corroded ("Weekly Checks").
• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Preheating system faulty - diesel models (Chapter 5C).
• Choke mechanism incorrectly adjusted, worn or sticking - carburettor petrol models (Chapter 4A).
• Fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Other ignition system fault - petrol models (Chapters 1A and 5B).
• Fast idle valve incorrectly adjusted - diesel models (Chapter 4D).
• Low cylinder compressions (Chapter 2A or 2B).

Engine difficult to start when hot

• Air filter element dirty or clogged (Chapter 1A or 1B).
• Choke mechanism incorrectly adjusted, worn or sticking - carburettor petrol models (Chapter 4A).
• Fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Low cylinder compressions (Chapter 2A or 2B).

Starter motor noisy or excessively-rough in engagement

• Starter pinion or flywheel ring gear teeth loose or broken (Chapters 2A and 5A).
• Starter motor mounting bolts loose or missing (Chapter 5A).
• Starter motor internal components worn or damaged (Chapter 5A).

Engine starts, but stops immediately

• Loose or faulty electrical connections in the ignition circuit - petrol models (Chapters 1A and 5B).
• Vacuum leak at the carburettor/throttle body or inlet manifold - petrol models (Chapter 4A, 4B or 4C).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).

Engine idles erratically

• Air filter element clogged (Chapter 1A or 1B).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Uneven or low cylinder compressions (Chapter 2A or 2B).
• Camshaft lobes worn (Chapter 2A or 2B).
• Timing belt incorrectly tensioned (Chapter 2A or 2B).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty injector - diesel models (Chapter 4D).

Engine misfires at idle speed

• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Faulty spark plug HT leads - petrol models (Chapter 1A).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty injector - diesel models (Chapter 4D).
• Distributor cap cracked or tracking internally - petrol models (where applicable) (Chapter 1A).
• Uneven or low cylinder compressions (Chapter 2A or 2B).
• Disconnected, leaking, or perished crankcase ventilation hoses (Chapter 4E).

Engine misfires throughout the driving speed range

• Fuel filter choked (Chapter 1A or 1B).
• Fuel pump faulty, or delivery pressure low (Chapter 4A, 4B or 4C).
• Fuel tank vent blocked, or fuel pipes restricted (Chapter 4A, 4B or 4C).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Faulty spark plug HT leads - petrol models (Chapter 1A).
• Faulty injector - diesel models (Chapter 4D).
• Distributor cap cracked or tracking internally - petrol models (where applicable) (Chapter 1A).
• Faulty ignition coil - petrol models (Chapter 5B).
• Uneven or low cylinder compressions (Chapter 2A or 2B).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).

Engine hesitates on acceleration

• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses (Chapter 4A, 4B or 4C).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty injector - diesel models (Chapter 4D).

Engine stalls

• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Fuel filter choked (Chapter 1A or 1B).
• Fuel pump faulty, or delivery pressure low - petrol models (Chapter 4A, 4B or 4C).
• Fuel tank vent blocked, or fuel pipes restricted (Chapter 4A, 4B, 4C or 4D).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty injector - diesel models (Chapter 4D).

Engine lacks power

• Timing belt incorrectly fitted or tensioned (Chapter 2A or 2B).
• Fuel filter choked (Chapter 1A or 1B).
• Fuel pump faulty, or delivery pressure low (Chapter 4A, 4B or 4C).
• Uneven or low cylinder compressions (Chapter 2A or 2B).
• Worn, faulty or incorrectly-gapped spark plugs - petrol models (Chapter 1A).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty injector - diesel models (Chapter 4D).
• Injection pump timing incorrect - diesel models (Chapter 4D).
• Brakes binding (Chapters 1 and 9).
• Clutch slipping (Chapter 6).

Engine backfires

• Timing belt incorrectly fitted or tensioned (Chapter 2A).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).

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Oil pressure warning light on with engine running

• Low oil level, or incorrect oil grade ("Weekly checks'").
• Faulty oil pressure warning light switch (Chapter 5A).
• Worn engine bearings and/or oil pump (Chapter 2C).
• High engine operating temperature (Chapter 3).
• Oil pressure relief valve defective (Chapter 2A).
• Oil pick-up strainer clogged (Chapter 2A).

Engine runs-on after switching off

• Excessive carbon build-up in engine (Chapter 2C).
• High engine operating temperature (Chapter 3).
• Faulty fuel cut-off solenoid - carburettor petrol models (Chapter 4A).
• Fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).
• Faulty stop solenoid - diesel models (Chapter 4D).

Engine noises

Pre-ignition (pinking) or knocking during acceleration or under load

• Ignition timing incorrect/ignition system fault - petrol models (Chapters 1A and 5B).
• Incorrect grade of spark plug - petrol models (Chapter 1A).
• Incorrect grade of fuel (Chapter 4A, 4B, 4C or 4D).
• Vacuum leak at the carburettor/throttle body, inlet manifold or associated hoses - petrol models (Chapter 4A, 4B or 4C).
• Excessive carbon build-up in engine (Chapter 2C),
• Blocked carburettor jet or internal passages - carburettor petrol models (Chapter 4A).
• Blocked injector/fuel injection system fault - fuel-injected petrol models (Chapter 4B or 4C).

Whistling or wheezing noises

• Leaking inlet manifold or carburettor/throttle body gasket - petrol models (Chapter 4A, 4B or 4C).
• Leaking exhaust manifold gasket or pipe-to-manifold joint (Chapter 4A, 4C or 4D).
• Leaking vacuum hose (Chapters 4A, 4B, 4C, 4D, 5B).
• Blowing cylinder head gasket (Chapter 2A or 2B).

Tapping or rattling noises

• Worn valve gear or camshaft (Chapter 2A or 2B).
• Ancillary component fault (coolant pump, alternator, etc) (Chapters 3, 5A, etc).

Knocking or thumping noises

• Worn big-end bearings (regular heavy knocking, perhaps less under load) (Chapter 2C).
• Worn main bearings (rumbling and knocking, perhaps worsening under load) (Chapter 2C).
• Piston slap (most noticeable when cold) (Chapter 2C).
• Ancillary component fault (coolant pump, alternator, etc) (Chapters 3, 5A, etc).