Bosch 0445110654 Common Rail Injector – The Service-Balanced Solution for Mercedes OM642 & BMW M57 Diesel Platforms

Q1: Can I replace a single 0445110654 injector, or do I need to replace all six?
You can replace a single injector, provided the new unit has the correct IMA code entered into the ECU. The ECU's adaptation range can handle up to a 3% flow difference between cylinders. However, if the remaining injectors have high mileage (> 80,000 km), their return flow will likely be elevated, and the new injector will deliver more fuel than the worn ones – this may cause a noticeable idle vibration. Replacing all injectors in a set is recommended for optimal performance.

Q2: How do I distinguish between a bad injector and a bad high-pressure pump?
Perform a leak-off test: if one or two injectors show significantly higher return flow (above 35 ml/min), the injectors are the cause. If all injectors show elevated return flow (above 25 ml/min each), the pump may be worn and sending insufficient pressure. Additionally, if the engine starts well but loses power above 3,000 rpm while the return flow is normal, suspect the fuel pressure regulator or the HP pump.

Q3: What is the correct way to measure the injector's return fuel flow?
Disconnect the fuel return line from the injector and connect a clear hose to a graduated cylinder. Run the engine at idle for 60 seconds (fuel temperature should be between 40–60°C, as viscosity affects flow rate). A healthy injector returns ≤18 ml/min; values above 30 ml/min indicate internal wear. Always measure all injectors and compare – a variation of more than 8 ml/min between the highest and lowest cylinders suggests a faulty injector.

Q4: Can the 0445110654 be used in the older 1,600 bar systems (like early OM642) without issue?
Yes, the injector will operate at lower pressures without damage – the 1,800 bar rating is a maximum, not a minimum. However, its flow characteristics at low pressure may be slightly different than the original injector (the 0654 is calibrated for a 1,800 bar system, so its opening and closing behaviour may differ). The ECU's adaptation should compensate, but some users report a slightly rougher idle until the adaptation completes (typically after 50–100 km).

Q5: What should I do if the IMA code label is unreadable on my new injector?
The IMA code is also printed inside the plastic packaging sleeve and often on the box label. If both are unreadable, some diagnostic tools can retrieve the code by reading the injector's internal memory, but this requires a Bosch-specific scanner. If the code cannot be retrieved, the injector cannot be used – returning the injector for an exchange is the only solution, as using it without the code will cause rough operation and a persistent DTC.

Q6: Can I use biodiesel (B20) with the 0445110654 injector?
Bosch approves B20 for the 0445110654. However, biodiesel's higher viscosity increases return flow by approximately 2–3 ml/min, and its solvent effect may cause tank deposits to become dislodged, clogging the injector's inlet filter. For B20 operation, reduce the primary filter change interval to 15,000 km (from the usual 20,000–25,000 km) and monitor the return flow monthly. If the return flow rises above 25 ml/min and the engine has only been running on B20, consider reducing the blend or increasing the frequency of filter changes.