Bosch 0445120287 / 0445120288 Common Rail Injector – High-Flow Variants for Performance Diesel & Large-Bore Applications

Q1: Can the 0445120288 replace the 0287 to gain more power without ECU changes?
No – the 0288 delivers 8% more fuel at the same pulse width, which will cause the engine to run rich, increasing soot and potentially damaging the DPF. It is permissible only if the ECU is reflashed with the 0288's injector data set, and the fuel map is adjusted for the higher flow. For power gains, this is a common tuning route, but it requires professional calibration.

Q2: Why does my engine exhibit a rough idle after installing new 0287 injectors, even after entering the IMA codes?
The ECU requires an "adaptation reset" after new injectors are installed – the learned offsets from the old injectors remain in memory and conflict with the new ones. Perform a "fuel trim reset" using diagnostic software (e.g., Bosch ESI-tronic or OEM tools), then run the engine at 2,000 rpm for 5 minutes to relearn the values. If roughness persists, check that the correct IMA code was entered – a single digit error changes the calibration by 2%.

Q3: How do I identify whether my engine requires the 0287 or the 0288 injector?
Check the vehicle's VIN and engine code – Mercedes engines with 170–190 kW use 0287; Audi/VW 3.0 TDI with 176–200 kW use 0288. Alternatively, consult the Bosch ESI application list – the part number is also visible on the injector's body label, though this may have faded over time. If in doubt, consult the vehicle's service documentation or a dealer.

Q4: What is the impact of low cetane fuel on these high-pressure injectors?
Low cetane (below 45) increases ignition delay, causing a harsher pressure rise that stresses the injector's needle and seat. The solenoid opens at the same timing regardless of cetane, so the fuel burns later, increasing exhaust temperatures and potentially causing the ECM to reduce the rail pressure as a protective measure, reducing power. Use a cetane booster if operating in regions with poor fuel quality.

Q5: Can I use the 0288 in a 1,600 bar system (like older OM642) to gain durability?
Yes, the injector will operate without issue at lower pressures – the higher pressure rating is a safety margin, not a minimum requirement. However, the increased needle lift of the 0288 may change the injection rate at low pressure, resulting in slightly rougher idle (≈1–2% variation) compared to the 0287. For most users, the difference is imperceptible, but for precision applications, matching the injector to the system is recommended.

Q6: What is the typical service interval for these injectors in a passenger car (15,000 km/year)?
In normal driving conditions, the injectors last 150,000–200,000 km before the return flow exceeds 35 ml/min at idle. However, short urban trips (where the engine rarely reaches operating temperature) can accelerate coking and reduce the interval to 100,000 km. Use fuel additive cleaners annually to extend nozzle life, and monitor the return flow at each service – a sudden increase above 25 ml/min is an early warning.