Bosch 0445117021 Diesel Injector

On the 3.0L V6 TDI platform, a failing Bosch 0445117021 injector typically presents as: uneven or unstable idle; ticking or knocking from the engine; hard or intermittent starting; hissing / chuffing with exhaust smell when an injector washer leaks; reduced power, hesitation or limp mode with warning lights.

When two or more of these appear together, suspect the injector before peripheral systems — a comparative leak-off test and live-data cylinder-balance review will isolate the failed unit without tear-down.

The documented failure modes on this platform are: piezo injector electrical faults logging group supply-voltage codes; injector correction values drifting out of range as the piezo stack ages; injector sealing washer leaks allowing combustion blow-by around the injector.

Internal wear cannot be repaired in situ — once delivery drifts outside calibration, remanufacture or replacement is the reliable fix.

Compare injector balance / correction values across all six cylinders — an outlier identifies the failing unit. On group supply-voltage codes, check the injector harness and connectors for open circuits before replacing hardware. Check return flow to identify a hydraulically defective injector. Injector coding is required after fitting — follow the manufacturer procedure.

Never condemn a common-rail injector on a fault code alone — codes identify the circuit or cylinder, while leak-off volumes and correction values identify the component.

Each remanufactured 0445117021 is fully stripped, ultrasonically cleaned and inspected; worn components are replaced with OE-grade parts. The rebuilt unit is then calibrated on a common-rail test bench against the manufacturer's specification sheet — delivery, back-leak and response are all verified before the injector is sealed and despatched with its calibration data on file.

Every unit carries a 12-month parts warranty and free UK delivery.

The 0445117021 trusted family covers 4 verified vehicle fitments across 3 makes: Audi, Volkswagen and Porsche. Every fitment listed on this page is registry-verified — no scraped or assumed applications.

0445117021 supersedes or cross-references 10 further OE numbers, including 0445117028, 0445117076, 0445117022, 0986435413, 0445116076, 059130277AS, 059130277CD and 059130277EJ. Always match the reference etched on your failed unit's body — cross-references within a family are verified equivalents, but etched numbers remain the source of truth.