0445020538 Bosch CP4 High-Pressure Fuel Pump for Yanmar and Thermo King

Genuine new Bosch 0445020538 CP4 high-pressure common rail fuel pump (Bosch type CR/CP4N1/L45/20, Yanmar OE 129C28-51000) for Yanmar 3TNV, 4TNV and JH-series diesel engines used in Thermo King transport refrigeration units, Bobcat compact equipment, marine drives and other off-highway machinery. It replaces the earlier Bosch number 0445020509 (Yanmar 129A00-51000). Supplied brand-new in the sealed Bosch box, made in Czech Republic, with a 1-year manufacturer warranty.

The CP4 is a single-plunger, camshaft-driven high-pressure pump. It draws low-pressure fuel through its integrated metering unit and delivers it to the common rail at the pressure the engine ECU demands, giving precise injection timing and quantity across the load range. As a mechanical high-pressure pump it is a fit-and-run replacement when the Bosch or Yanmar number matches your original.

Also known internationally as: High-Pressure Fuel Pump / Common Rail Pump (EN), Hochdruckpumpe / Common-Rail-Pumpe (DE), Pompe haute pression / Pompe common rail (FR), Pompa ad alta pressione / Pompa common rail (IT), Bomba de alta presion / Bomba common rail (ES), Pompa de inalta presiune / Pompa de injectie common rail (RO) - Bosch 0445020538 for Yanmar and Thermo King.

Key features

Product details

OEM cross-reference numbers

Compare your original part number before ordering. The vehicle or engine model alone is not enough to confirm compatibility - verify by the number on the pump fitted to your engine.

Vehicle and machine compatibility

Compatibility must always be verified by the original part number, OEM number, VIN or engine serial number. The engine model alone is not sufficient. The Yanmar 3TNV / 4TNV engines below are widely used in Thermo King transport refrigeration units, Bobcat compact equipment and other industrial and off-highway machinery; the JH-series engines are Yanmar marine engines.

Technical information

Related diesel fuel system components

These are the Bosch fuel system parts fitted alongside this pump on the Yanmar engines above. Manufacturers used different variants depending on engine build, power rating, emissions standard and production date, so another code may be the correct one for your engine - always identify the exact part by the number stamped on the unit fitted to your engine, not by the engine model alone.

Where one engine code lists two injector part numbers, both were fitted in production at different times: 4TNV88C uses 0445110463 or 0445110679; 4TNV98C uses 0445110507 or 0445110969; 4TNV98CT uses 0445110508 or 0445110970. Confirm the correct injector by the number on the unit fitted to your engine.

Shipping and warranty

Frequently asked questions

How do I know the Bosch 0445020538 fits my Yanmar engine or Thermo King unit? Match the number on the pump currently fitted to your engine, or the Yanmar number 129C28-51000, against this listing. This pump also replaces the earlier Bosch 0445020509 (Yanmar 129A00-51000). The engine model alone is not enough - confirm by the part number, OE number or engine serial.

Is 0445020509 the same pump as 0445020538? 0445020538 is the current Bosch number and replaces the earlier 0445020509 (Yanmar 129A00-51000). They share the same application on these Yanmar engines. If your original is marked 0445020509, this pump is the correct up-to-date replacement.

Is it new or remanufactured? This is a genuine new Bosch pump in the sealed manufacturer box, not a remanufactured exchange unit. There is no core charge on this item.

Does the pump need coding or programming after fitting? No. This is a mechanical high-pressure pump, so it needs no ECU coding. Fit the pump, then prime and bleed the fuel system following the engine manufacturer's procedure.

What is CR/CP4N1/L45/20? It is the Bosch internal type designation laser-etched on the pump. CP4 is the pump series; the single-plunger configuration handles the fuel volume of these 3 and 4 cylinder Yanmar engines.

Which fuel rail and injectors go with this pump? The 3-cylinder engines use rail 0445213022 and the 4-cylinder engines use rail 0445214271; the injectors vary by engine code (see the related components table). Identify each by the number on the part fitted to your engine.

Do you ship worldwide? Yes, we ship worldwide.

What is included? One new Bosch 0445020538 high-pressure pump. Mounting seals or gaskets are not included and should be renewed from your original where required.

Common symptoms of a failing CP4 high-pressure pump

Hard or no starting, loss of power, rough running and low-rail-pressure fault codes are typical signs of a worn or failing high-pressure pump on these Yanmar common rail engines. Because contaminated or water-in-fuel damage is a common cause, have the fuel system and filtration checked and the fault confirmed by a diesel specialist before replacing parts.