Injectors Faults

Glow plug failure on the 1.4 TDI Fabia causes white smoke and hard cold starting. The engine's small combustion chamber is particularly reliant on glow plugs in cold UK winters.

High-mileage Insignia CDTi examples develop injector wear, causing rough running and rising oil levels from diesel contamination.

The Corolla Mk9 diesel is generally reliable, but DPF blockage affects city-driven examples and injector fouling occurs at high mileage. Toyota quality means these are manageable issues.

High-mileage A4 B8 TDIs suffer injector wear, causing rough running, smoke and diesel contamination of engine oil.

The K9K injector fuel return pipe clips crack with age — a fire risk found on all K9K-powered Renaults including the Megane. The repair is inexpensive but urgent.

The K9K injector fuel return pipe clips crack and leak diesel. It is a fire risk if left unaddressed and affects all K9K-engined vehicles including the Juke.

Injector wear on the 1.2 TDI causes rough running and smoke. The three-cylinder engine runs with high injection pressures that accelerate injector wear.

Unlike the older PD-engine Passats, the B7 common rail 2.0 TDI uses a timing belt. The belt interval is 140,000 miles but many specialists recommend 100,000 miles given the cost of engine damage.

High-mileage Transit Customs suffer injector wear, causing diesel to contaminate the engine oil. This is a serious secondary failure that must be caught early.

High-mileage Passat B7 TDIs suffer injector wear. The common rail system operates at extreme pressure and injector precision degrades with use.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

Diesel glow plugs burn out over time causing cold starting issues. The major problem is they often snap in the cylinder head when mechanics try to remove them.

The Volvo D2 uses the PSA 1.6 HDi engine. The copper seals at the base of the injectors fail, allowing exhaust gases to escape. Often termed 'The Black Death'.

A fatal flaw in the Mazda 2.2 MZR-CD engine. Injector seals leak, allowing carbon into the oil sump which blocks the oil pickup strainer. The engine then seizes from oil starvation.

The 2.2 D-CAT (Diesel Clean Advanced Technology) engine is perhaps Toyota's least reliable engine. It suffers from massive carbon buildup, 5th injector failure, and head gasket blow-outs.

Early OM651 engines (2008-2012) were fitted with Delphi piezoelectric injectors that failed so frequently it resulted in a massive global recall and class-action lawsuits.

While replacing blown glow plugs is normal maintenance, on the 1.3 CDTi they are notoriously long, thin, and seize into the cylinder head.

Ford uses a 5th injector (vaporiser) in the exhaust to regenerate the DPF. This vaporiser clogs with soot, preventing regeneration.

The Siemens VDO injectors used on the 1.8 TDCi are highly prone to electrical failure, dropping the car to 3 cylinders.

The 1.6 TDI uses Siemens/Continental piezo injectors which are incredibly prone to sudden electrical failure, causing immediate engine shutdown.

Early 1.5 dCi engines (K9K) used Delphi fuel injectors that were highly prone to failure, causing misfires and sometimes producing metal swarf that destroys the entire fuel system.

Copper injector seals fail, allowing exhaust gases and unburnt diesel to escape and coat the top of the engine in a hard black tar affectionately known as 'Black Death'.

The High Pressure Fuel Pump on the N14 engine fails frequently. It is one of the most well-known and expensive failures on the R56 Cooper S.

The tandem pump (which provides vacuum for brakes and fuel pressure for injectors) is prone to leaking. It can leak diesel externally, or worse, leak diesel internally into the engine oil.

The wiring loom that connects the PD injectors sits inside the cylinder head, submerged in hot engine oil. The insulation degrades, causing misfires and injector faults.

The N47 relies on Bosch piezoelectric injectors. These wear internally, causing over-fuelling, rough idling, and potentially piston damage if they stick open.

A blocked DPF on the N47 is highly common, often a secondary symptom of thermostat failure, glow plug module failure, or exclusively urban driving.

Injector failure on the 1.3 CDTi causes rough running, misfires and black smoke under acceleration. The piezoelectric injectors used in this engine are expensive to replace.

Failed glow plugs on the 1.5 TDCi cause difficult cold starting, white smoke and misfire on startup. Often overlooked on service schedules, they are a high-mileage wear item.

Injector copper sealing washers on the Astra J 1.6 CDTi harden and allow combustion gases to bypass the injector seat. This causes carbonisation around the injector tops and eventually rough running.

The high-pressure fuel pump on the 1.3 CDTi can fail, causing hard starting, rough running and eventually preventing the engine from starting. It is an expensive repair relative to the car's value.

Common rail injectors on the 1.5 TDCi can fail, causing misfires, excessive smoke and hard starting. Injector failure can also result in diesel washing the cylinder walls, accelerating engine wear.

Common rail injector failure on the Focus Mk3 TDCi causes rough running, misfires and in severe cases, diesel contamination of the engine oil. Worn injectors dribble fuel continuously.

Glow plug failure on the Focus Mk3 TDCi is a common higher-mileage issue. Failed plugs cause white smoke and rough running when cold, clearing quickly once the engine reaches temperature.

The copper seating washers and O-ring seals on the 1.6 TDCi injectors harden with heat cycling and allow diesel to weep past the injector body. This causes a fuel smell and carbon build-up around the injector tops.

Failed glow plugs on the Corsa D 1.3 CDTi cause white smoke and hard cold starting. The 1.3-litre engine has a small combustion chamber that relies heavily on glow plugs in cold UK winters.

Injector failure on the Z17DTH engine causes misfires, rough running and in advanced cases prevents starting. The solenoid-type injectors used in this engine respond well to professional cleaning.

The same critical cam follower issue as the Golf Mk5 — the HPFP cam follower wears through to the camshaft. A £15 inspection and part replacement prevents a £2,500 camshaft repair.

The Octavia Mk2 TDI PD engine shares the VAG cam follower weakness. Because Octavias are often high-mileage fleet or family cars, this issue is widespread — and many used cars are sold without the seller knowing the cam lobe is destroyed.

The K9K 1.5 dCi in the Clio Mk3 has a known failure on the injector fuel return pipes. The plastic fittings crack and cause a fuel leak — a fire risk that must be addressed immediately.

The PD (pumpe-düse) 2.0 TDI uses a mechanical cam follower to drive the high-pressure fuel pump. This follower wears rapidly and if not replaced destroys the camshaft — a £2,500 repair for a £15 part.