0445020538 Bosch CP4 High-Pressure Fuel Pump 129C28-51000 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. The CP4 is lubricated by the diesel it pumps, which is why fuel cleanliness and filtration determine its service life.

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.

What condition is this pump supplied in? It is a genuine new Bosch pump in the original sealed Bosch box, made in Czech Republic, with a 1-year manufacturer global warranty. There is no core charge on this item, so no old part has to be returned.

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.

What causes a CP4 pump to fail? The CP4 is lubricated by the diesel it pumps, so poor fuel quality, water in the fuel, contamination, air ingress or a neglected fuel filter are the usual causes. Running the tank dry is also damaging, because it removes lubrication from the pump.

Can a failed CP4 pump damage the injectors and rail? Yes. When a CP4 fails internally it can release metallic debris (swarf) throughout the fuel system, not only on the high-pressure side. In that case the entire circuit - fuel tank, in-tank (low-pressure) electric feed pump, supply and return lines, fuel filter and housing, high-pressure pump, common rail, rail-pressure sensor, fuel metering unit and injectors - must be inspected and decontaminated, and any component that cannot be reliably and completely cleaned (typically the in-tank electric fuel pump, the rail-pressure sensor, the fuel metering unit and, in most cases, the injectors) must be replaced rather than reused. Otherwise the new pump can fail again quickly.

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 injection pump

On the Yanmar 3TNV, 4TNV and JH-series common rail engines, a worn or failing CP4 high-pressure pump typically presents as extended cranking or a no-start condition, an engine that starts and then stalls shortly afterwards, reduced power under load, unstable or low rail pressure with corresponding low-rail-pressure diagnostic trouble codes, and, in the advanced stages of internal wear, metallic particles in the fuel filter. Because these symptoms overlap with injector, fuel metering unit, rail-pressure sensor and low-pressure fuel supply faults, the complete fuel system must be diagnostically tested before the pump is replaced, to confirm the pump is the actual cause of the fault.

If the pump has failed internally and generated metallic debris (swarf), cleaning the high-pressure circuit alone is not sufficient. The entire fuel system must be inspected and decontaminated from the tank through to the injectors inclusive - fuel tank, in-tank (low-pressure) electric feed pump, all supply and return lines, the fuel filter and its housing, the high-pressure pump, the common rail, the rail-pressure sensor, the fuel metering unit and the injectors. Any component that cannot be reliably and completely cleaned - typically the in-tank electric fuel pump, the rail-pressure sensor, the fuel metering unit and, in most cases, the injectors - must be replaced rather than reused. Installing a new CP4 pump into a system that still contains metallic contamination is the most common cause of an immediate repeat failure.

Before installation

Before the new pump is fitted, the fuel supply system must be checked for contamination. Rust, water, sludge or varnish-like deposits, metallic debris or any other contaminant left in the tank, supply and return lines, filter housing or rail will damage the new pump within a short service period, and that damage is not covered by the warranty. Inspect and decontaminate the system, renew the filters and confirm that the fuel is clean before installation.