Mercedes-Benz Sprinter: OM651 Bosch CP4 Fuel Pump Metal Debris Contamination

The Bosch CP4.1 high-pressure fuel injection pump fitted to the OM651 2.1CDI engine is susceptible to internal plunger and bore wear that releases fine metal particles into the high-pressure fuel circuit. These particles are distributed throughout the fuel rail and common-rail injectors, causing injector failure and frequently requiring replacement of the entire high-pressure fuel system including the pump, fuel rail, all injectors, and high-pressure lines. Failure can be sudden and leads to a no-start condition. Lower-lubricity fuel and cold-start operating conditions are known aggravating factors.

• Sudden loss of engine power or vehicle failing to start
• Multiple injector fault codes stored simultaneously on scan tool
• Metal particles or fine metallic debris visible in fuel filter element
• Rough running with high-pressure fuel system fault codes

1. 1

   Ask the owner about any history of hard starting, sudden power loss, or fuel system component replacements.

2. 2

   If a workshop inspection is possible: Connect a diagnostic scanner and check for multiple simultaneous injector fault codes or high-pressure rail pressure faults.

3. 3

   Remove and inspect the fuel filter element for metallic debris or a fine silver-grey residue — any metal contamination confirms pump failure and system-wide contamination.

Parts involved: High-pressure fuel pump.

$6,000 to $20,000 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the fuel filter ever been inspected for metal debris or replaced due to contamination?”
• “Has the vehicle ever experienced sudden power loss or a no-start event?”
• “Has the fuel pump, fuel rail, or any injectors been replaced?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.