P0206: How to Diagnose & Fix — Injector Circuit/Open - Cylinder 6

The 2017-2023 Ford Transit with the 2.0L EcoBlue diesel engine (available in some markets) and the 3.5L EcoBoost V6 experience fuel injector failures causing rough running, misfires, poor idle, reduced performance, and excessive smoke on cold start. Ford issued a service action for 2.0L EcoBlue vehicles built between February and September 2019 after a batch of high-pressure fuel injectors (reported as Continental-supplied) failed to meet quality standards, causing misfire and reduced engine performance. FordTransitUSAForum.com documents injector failure on 3.5L EcoBoost Transit models as well, where direct injection fuel deposits cause injector spray pattern degradation. RepairPal estimates individual injector replacement between $266 and $627 depending on Transit model, but multiple injectors often need replacement simultaneously, and contaminated fuel systems can cost significantly more.

The fuel injectors on the Duramax LML (Bosch piezoelectric) and L5P (Denso solenoid) engines can fail due to contaminated fuel, high-mileage wear, or internal electrical faults. A failed injector causes white smoke on startup, rough idle, misfires on the affected cylinder, and fuel dilution of the engine oil. The high fuel rail pressures (about 29,000 PSI on the L5P) stress the injectors over time. Contaminated fuel from bulk diesel stations accelerates injector wear.

The FSI direct-injection injectors shared across the VAG family (Audi/VW/Porsche) are a documented R8 failure point. Injectors can stick open or closed; a stuck-open injector dumps raw fuel into the cylinder and can wash down the bore, while a stuck-closed injector starves the cylinder. One well-known r8talk case had 6 of 8 injectors fail on a 2008 V8 at only 14,000 miles. Symptoms overlap with coil failure (misfires), so proper diagnosis is important, and carbon buildup on the injector tips is a contributing factor.

The 2001-2004 6.6L Duramax RPO LB7 uses injectors buried under the valve covers that are notorious for failing well before 150,000 miles. GM's own analysis attributed the failures to fuel injector body cracks, ball seat erosion, and high-pressure seal extrusion. A leaking injector dumps unburned diesel into the cylinder and past the rings into the crankcase, raising the oil level and diluting it. Owner reporting on duramaxforum.com and silveradosierra.com consistently puts first failures in the 100k-150k range, and because the injectors sit under the valve covers the labor to reach them is far higher than on the later LLY/LBZ engines, where injectors are accessible from the top. This is an LB7-only failure mode - the LLY and later injectors were redesigned and do not share it.

These F-250s used two different 7.3L diesels. The older IDI has simple mechanical injectors. The 7.3L Power Stroke arrived midway through the 1994 model year and uses hydraulically actuated, electronically controlled (HEUI) injectors. Injectors on both engines wear with age and miles. On the Power Stroke, internal wear can make an injector bleed off pressure or spray poorly. Failed seals can let fuel get into the engine oil or coolant, and the electrical solenoid can fail before the mechanical parts do. One diesel reference puts average injector life near 150,000 miles, with some failing around 100,000 and others passing 200,000. Each injector has separate fuel and oil chambers, so the quality of both fluids strongly affects injector life. 1994-1995 trucks and 1996-1997 federal-emissions trucks use single-shot "AA" injectors. 1996-1997 California-emissions trucks use split-shot "AB" injectors. On the IDI, owners report that injector springs weaken over time, so the injectors open early. This causes a fuel knock that can sound like a rod or main bearing knock. Owners also report injectors that stick open. Owners say similar symptoms can come from injection-pump timing or from a leaking lift pump (which puts fuel in the oil), so the injectors are not always the cause.