I. Core Specifications (OEM Standard)

OE Model: 185366190 (Perkins OEM), TPN257 (Generic Code)

Voltage: 12V (Rapid-Heat Type)

Thread Specification: M10 × 1.25

Overall Length: Approx. 81.6 mm

Heating Tip Length: Approx. 22.5 mm

Installation Torque: 20–25 N·m

II. Compatible Engines (400 Series)

403C-15 (The model you searched for)

403D-15, 403D-17, 404C-22, 404D-22

III. Cross-Reference Models

Perkins OEM: 185366060, 185366092, 185366180, 185366210

IV. Selection and Replacement Tips

Voltage Verification: This model is 12V; it must not be used in 24V systems.

Full Set Replacement: The 403C-15 is a 3-cylinder engine; it is recommended to replace all 3 glow plugs simultaneously to ensure uniform heating. 

Installation Essentials: Clean the threaded holes, apply a small amount of anti-seize compound, and tighten to the standard torque specification to prevent air leaks or damage.