Carbon Build-Up Faults

16 known faults tagged with Carbon Build-Up

EGR Valve Failure

2007-201440,000–90,000 miles£80–£350

EGR valve carbon build-up on the 1.4 TDI Fabia restricts airflow and causes power loss. The small engine is particularly sensitive to EGR restriction.

Turbocharger Variable Vane Failure

Severe

2005-201470,000–140,000 miles£200–£1050

The variable-vane turbocharger on the 1.9 CDTi Zafira develops sticky vanes from carbon build-up, causing limp mode and poor performance.

EGR Valve Failure

Moderate

2007-201350,000–100,000 miles£100–£450

EGR failure on the 308 HDi causes the familiar symptoms of power loss and rough running. The PSA 1.6 HDi EGR system is well-known for carbon build-up.

EGR Valve Carbon Build-Up

Moderate

2012-201940,000–90,000 miles£100–£450

EGR failure on the 208 BlueHDi follows the established PSA pattern — carbon deposits restrict the valve, causing power loss and rough running.

EGR Valve Carbon Blockage

Moderate

2008-201650,000–100,000 miles£100–£400

EGR valve carbon build-up on the Megane Mk3 dCi restricts airflow and causes power loss. It is one of the most frequently reported faults by Megane diesel owners.

EGR Valve Failure

Moderate

2006-201350,000–100,000 miles£100–£400

EGR failure on the Note dCi produces power loss and rough running. The small engine is sensitive to any reduction in airflow caused by EGR carbon build-up.

EGR Valve Failure

Moderate

2007-201460,000–120,000 miles£200–£450

EGR failure on the Mondeo Mk4 TDCi causes power loss and rough running. Carbon build-up on the valve is the primary cause, accelerated by urban use.

Turbocharger Variable Vane Sticking

Severe

2013-202160,000–130,000 miles£200–£1000

The VNT turbocharger on the 2.0 TDCi Transit Custom develops sticky variable vanes from carbon build-up, causing power loss and limp mode.

2.2 D-CAT Head Gasket and Carbon Blockage

Critical

2006-201270,000–120,000 miles£2000–£3500

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.

EGR Valve Failure and Anti-Shudder Valve

Moderate

2003-201370,000–140,000 miles£200–£350

The EGR valve and the adjacent anti-shudder valve (throttle flap) are prone to failing due to heavy carbon buildup and stripped internal plastic gears.

Carbon Build-up on Intake Valves

Moderate

2006-201040,000–80,000 miles£200–£350

Because the N14 is a direct-injection engine, fuel does not wash over the intake valves. Oil vapor from the PCV system bakes onto the hot valves, causing severe carbon build-up.

EGR Valve Failure and Intake Carbonisation

Moderate

2013-201740,000–90,000 miles£80–£350

EGR failure on the 1.5 TDCi Fiesta is a common companion to DPF issues. Carbon deposits block the valve and intake manifold, causing power loss and rough running.

EGR Valve Failure

Moderate

2004-201050,000–100,000 miles£80–£350

The Isuzu-sourced Z17DTH and Z17DTJ engines in the Astra H have a well-documented EGR valve failure. Carbon deposits cause the valve to stick, resulting in power loss and increased emissions.

Injector Seal Failure and Diesel Weeping

Moderate

2004-201170,000–140,000 miles£150–£300

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.

EGR Valve Failure and Carbon Build-Up

Moderate

2006-201450,000–100,000 miles£80–£280

The Fiat/GM 1.3 CDTi is a capable diesel but its EGR valve blocks with carbon deposits regularly. This is one of the most common Corsa D complaints.

Carbon Build-Up on Intake Valves

Moderate

2006-201340,000–80,000 miles£300–£600

The N14's direct injection system means fuel is injected directly into the cylinder, bypassing the intake valves. Oil vapour from the PCV system coats the valves with carbon, causing power loss and misfires.