Mercedes Actros MP4 Bosch 0445 Injector Repair

Mercedes Actros MP4 / Antos / Arocs Bosch 0445 Common Rail Injector Repair Guide

Mercedes-Benz launched the fourth-generation Actros (internally called MP4 / New Actros) in 2011, with the Antos distribution and Arocs construction variants following. From model year 2012 onward, the OM471 (10.7L) and OM473 (12.8L) inline-6 Euro VI engines replaced the previous OM501 / OM502 PLD unit-injector system with a Bosch common rail architecture running at 2,160 bar. The injector changed with it: from a mechanical PLD (Pumpe-Leitung-Düse, single-component pump-nozzle) to a solenoid-driven Bosch CRI2 / 0445110-series common rail injector. This is the part that workshops across Europe, the Middle East, Africa, Russia, CIS and Latin America now see on the bench every week, and the failure modes are different from anything the previous PLD generation had.

This guide walks through what the Bosch 0445 injector is, how it is built, where it tends to fail, what the truck tells you when it does, and which BEACON MACHINE test bench is the right tool for the job. If you service Actros, Antos or Arocs trucks — fleet or independent — read on. If you only know the old PLD numbers (0 414 799 005 and similar), pay attention: the part number format and the diagnostic logic both changed.

Vehicle and Engine Coverage

Truck Model	Engine	Emission Level	Injector Family	Common OEM Reference
Actros MP4 (4th gen, 2011+)	OM471	Euro VI	Bosch CRI2 / 0445110	0445110293, 0445110354, 0445110400
Actros MP4 (4th gen, 2011+)	OM473	Euro VI	Bosch CRI2 / 0445110	0445110294, 0445110363, 0445110421
Antos	OM471 / OM936	Euro VI	Bosch CRI2 / 0445110	Shared with Actros
Arocs	OM471 / OM473	Euro VI	Bosch CRI2 / 0445110	Shared with Actros
Older Actros MP3 (OM501 / OM502)	OM501 / OM502	Euro V	Bosch PLD unit injector	0 414 799 005 (legacy)

The 0445110-series part numbers seen on Actros MP4 injectors are Bosch CRI2 (Common Rail Injector, generation 2) — a 4-pin electromagnetic solenoid design that is fully interchangeable across the OM471 and OM473 engines. Workshops that have invested in a CR919 or CR1016 can test the entire 0445 family directly from the system database; smaller workshops running an EPS205 need only the standard pressure line and the Beijing system add-on for full data coverage.

Inside the Bosch 0445 Injector — Component Breakdown

The Bosch 0445 CRI2 injector is a precision hydraulic assembly. Every part plays a specific role in the spray event, and every part is a potential wear point. The main components, from the combustion chamber end up, are:

• Nozzle (spray tip): Multi-hole (typically 7 or 9 micro-holes) precision-drilled steel, with a needle valve that opens and closes against a hardened seat. The holes are around 100–150 microns in diameter; even minor carbon buildup or erosion changes the spray pattern and atomisation quality.
• Nozzle nut (nozzle retaining nut): The hex nut that clamps the nozzle assembly to the injector body. Torqued to spec during manufacture; repeated disassembly without a proper holder damages the threads.
• Nozzle spring and shim(s): Sets the needle opening pressure. Stack height of the shim pack determines NOP. A shim that has been incorrectly reinstalled after cleaning changes opening pressure by 5–20 bar — enough to alter injection timing.
• Injector body: Houses the high-pressure fuel gallery, control piston (pilot valve), and the electromagnetic solenoid coil. The control piston is what translates solenoid movement into needle lift; wear here causes the classic "no fault code, but rough idle" symptom.
• Solenoid coil (4-pin): The two power pins energise the coil to open the injector; the two temperature/feedback pins report back to the ECU. Coil resistance is typically 0.5–1.5 Ω; insulation resistance should be > 100 MΩ. A coil with low insulation is the most common electrical failure.
• High-pressure inlet (orange protective cap): The fuel inlet from the rail, sealed with copper or steel sealing washers. The orange plastic cap is a shipping protection only — it must be removed before installation.
• Leak-off ports and O-rings: Two O-rings (one green FKM, one black) seal the injector in the cylinder head. A third O-ring seals the high-pressure inlet. The leak-off (return) gallery carries residual and spill fuel back to the tank.

Each of these parts has a specific failure mode, and the test procedure differs by which part has failed. A bench test that only measures flow at a single pressure point — common on the cheapest testers — will miss most of the early-stage problems. You need a tester that measures: full-load flow at 1,600 bar, idle flow at 250–300 bar, pre-injection (VL) volume, return fuel volume, and response time on the solenoid pulse. That is exactly what the BEACON EPS205 / EPS211 / CR217 do with the Beijing system database behind them.

Common Failure Points and What the Truck Tells You

Actros MP4 trucks spend their life at high load on motorway routes. The Bosch 0445 injector in these engines has a typical service life of 250,000–350,000 km before overhaul is needed, but specific failure modes appear much earlier depending on fuel quality, oil change intervals, and short-trip duty. Here are the failure modes BEACON MACHINE sees most often in customer returns.

1. Nozzle carbon build-up and hole erosion. This is the most common complaint. The truck shows rough idle, white smoke on cold start, and a 5–15% power loss at full load. On the bench, the injector passes full-load flow but fails the idle flow test — the needle is sluggish because the nozzle seat is glazed with carbon. Cleaning the nozzle with ultrasonic bath and lapping the seat is the right repair; replacing the nozzle is the alternative for severely eroded parts. The fault code is typically P0201–P0206 (cylinder N injector circuit malfunction) or P0300 (random misfire), not a flow code.

2. Control piston wear inside the injector body. The Actros shows a long crank time (5–8 seconds) on cold start, and at idle the engine hunts 30–50 rpm. No diagnostic trouble code is stored, because the ECU sees the injector as electrically healthy. The control piston is what regulates the opening speed of the needle; when its bore is worn, the pilot oil leaks and the needle does not lift cleanly. The bench test shows low VL (pre-injection) volume and a sluggish response curve. This injector cannot be repaired by cleaning — it needs a body replacement or a complete injector exchange.

3. Solenoid coil insulation breakdown. The truck goes into limp-home mode with a P0263 / P0266 / P0269 / P0272 (cylinder N contribution/balance fault) and a stored P0201–P0206 family code. This is the electrical failure: insulation between the coil windings and the body drops below 100 kΩ, and at high rail pressure the leakage current fools the ECU. Bench test: insulation resistance measurement between each pin and the injector body. The Beijing system on EPS205 / EPS211 / CR217 measures this directly. Repair: full coil replacement on a test stand, or injector exchange.

4. Leak-off O-ring failure. The truck shows diesel smell in the engine bay, hard starting after a hot soak, and a wet injector bore when the rocker cover is removed. This is the cheap fix — replace the O-rings and the copper inlet washer, and bench-test the injector to confirm it still meets flow specs after the seal work. Many workshops do not replace the O-rings at scheduled intervals, which is the root cause. The leak is from the high-pressure inlet seal, not from the injector itself, and the bench test will pass if the O-rings are the only issue.

5. Cracked or deformed high-pressure inlet fitting. The Actros idles roughly, drops cylinders at low speed, and shows a fuel rail pressure error code (P0087 / P0088). This is the less common mechanical failure — the inlet fitting where the high-pressure line from the rail attaches has developed a micro-crack from repeated torque cycling. Bench test shows unstable rail pressure during the test cycle. The repair is fitting replacement; the injector body itself is usually OK.

6. ECU-side driver failure (less common but possible). If multiple injectors fail at the same time, or if replacing the injector does not clear the code, the ECU final-stage driver is suspect. This is not an injector problem at all, but the bench test correctly returns a clean result, which is the diagnostic clue.

Why the EPS205 / EPS211 / CR217 are the Right Test Benches for This Work

BEACON MACHINE has shipped hundreds of these injectors through the bench. The Bosch 0445 family is fully covered in the Beijing system database, with 7,343 common rail data points across Bosch (2,393), Denso (4,187), Siemens (171), Delphi (449), CAT (17) and MTU (19) injectors. The 0445 injectors specifically have complete test plans that include the full-load flow test, the idle flow test, the leak test, the response time test, and the automatic comparison against factory-new reference data. The bench then reports pass / fail and identifies which test point failed, which is what you need to decide between clean, repair or replace.

The EPS205 is the entry-level bench for the Actros MP4 workshop. 2 kW servo motor, 220V single-phase only, CP1 high-pressure pump, 2,000 bar maximum pressure. It is the right tool for workshops that handle Bosch 0445 injectors as one of several services, where a full CR919 is overkill. The compact size (135 kg, 80×75×80 cm footprint) means it fits in a corner of the existing workshop without dedicated space. Beijing system with full 0445 test plans is included. CRIN2 piezo injector test is also supported (the 0445116-series is the piezo variant on later OM471 updates).

The EPS211 steps up to 4 kW motor, 220V single-phase or 380V three-phase, CP3 high-pressure pump, 2,400 bar maximum pressure. It adds simultaneous dual-injector testing (one flow sensor + one extra injector line) and a stronger cooling system, so a workshop running 6–10 Actros injectors per day does not overheat the oil. The 4 kW motor also handles the higher back-pressure of HEUI injectors if the workshop also services mixed fleets (Detroit, Volvo, Scania with Bosch pumps).

The CR217 is the workshop-favourite for serious Mercedes commercial-vehicle work. 5.5 kW motor, 380V three-phase, common rail + piezo + BIP as standard, plus the high-pressure pump test function and the Denso HP0 pump test. The CR217 is the bench to buy if the workshop services a Mercedes-only fleet and a mixed Actros / Antos / Arocs flow. Built as a direct alternative to OEM-equivalent benches — same database coverage, same 0445 test plans, with the same piezo support. Reach out to our team to discuss the configuration that fits your workshop. The CR217 also has the optional CP4 pump-test extension that the EPS205 / EPS211 do not include as standard.

Bench Test Procedure for Bosch 0445 on the BEACON EPS205 / EPS211 / CR217

The standard test plan, automatically loaded when the Bosch 0445110xxx part number is selected from the database, runs the following sequence:

1. Leak test (static): 30 seconds at 1,200 bar with the solenoid de-energised. Acceptable leak: less than 2 cm³/30s. A leaking injector at this stage points to nozzle seat wear.
2. Pre-injection volume (VL): Measure the small pilot injection volume at 250 bar. The 0445 spec is 2–6 mm³. Out-of-spec VL usually means the control piston is worn.
3. Full-load flow at 1,600 bar: Compare to the factory reference data within 5%. This is the main flow test — out of spec means nozzle wear or solenoid binding.
4. Idle flow at 250 bar: Compare to the factory reference data. Out of spec at idle but in spec at full load points to nozzle sluggishness — the cleaning/lapping repair case.
5. Response time: Time from solenoid energise to full needle lift. Spec: 0.3–0.6 ms. A slow response points to solenoid coil degradation or control piston wear.
6. Leak-off volume: Measure the return fuel over a 60-second cycle. Acceptable: less than 5 cm³/min. Higher leak-off is the O-ring failure case.
7. Insulation resistance: Measure between each pin and the injector body. Spec: > 100 MΩ at 500V. Lower than 1 MΩ means the coil has failed.

Total test time per injector on the EPS205 is about 4 minutes. On the CR217 with the dual-injector option, two injectors at once means the workshop runs 30 injectors per hour through the bench. This is the throughput difference between a workshop that is profitable on Actros service work and one that is not.

Mercedes Actros MP4 Injector Compatibility Table

Truck	Engine	Injector OEM	Test Plan	Recommended Bench
Actros MP4 / Antos / Arocs (2011+)	OM471 10.7L	0445110293, 0445110354, 0445110400	Bosch 0445 standard	EPS205 / EPS211 / CR217
Actros MP4 (later updates, Euro VI step D)	OM471 LA	0445116-series piezo	Bosch piezo + standard	EPS211 / CR217
Actros MP4 / Arocs (heavy duty)	OM473 12.8L	0445110294, 0445110363, 0445110421	Bosch 0445 standard	EPS205 / EPS211 / CR217
Arocs 8x4 / 8x6 (off-road / construction)	OM471 / OM473	Same as above	Bosch 0445 standard	EPS205 / EPS211 / CR217
Older Actros MP3 (2003–2011) for reference	OM501 / OM502	0 414 799 005 (PLD)	PLD unit injector, cam box	CR919 + cam box (not covered here)

Data compiled from BEACON MACHINE shipments and service records across European, Middle East, North African and CIS markets 2017–2026.

Voltage, Logistics and Language

• Voltage: The Actros MP4 / Antos / Arocs operates on 24V electrical, but the workshop test bench is independent. EPS205 is 220V single-phase only. EPS211 supports both 220V single-phase and 380V three-phase. CR217 is 380V three-phase. For sites on 110V or 127V supply (Latin America, North America), a 5 kW step-up transformer is available as an option. For sites on 220V three-phase, no transformer is required.
• Logistics: Wooden crate per machine, dimensions 97×87×104 cm (EPS211) or 100×100×110 cm (CR217), gross weight 190–360 kg. FOB Qingdao, CIF most major ports (Rotterdam, Hamburg, Constanta, Novorossiysk, Mersin, Jeddah, Alexandria, Mombasa, Santos, Veracruz, Buenos Aires). Sea freight 28–40 days depending on route. Air freight available for the EPS205/211 at the volumetric weight.
• Language: The Beijing system on all three benches supports 9 languages including English, Spanish, Russian, Arabic, French, Portuguese, German, Italian and Turkish. The interface is configured before shipment without additional charge.

BEACON MACHINE Service Record for Mercedes-Benz Commercial Vehicles

BEACON MACHINE has supplied diesel test equipment to Mercedes-Benz commercial vehicle workshops across more than 25 countries since 2014, including authorised service partners in Germany, Poland, Russia, Ukraine, Turkey, Egypt, Algeria, Saudi Arabia, UAE, South Africa, Nigeria, Kenya, Mexico, Brazil, Argentina, Chile, Peru, Colombia, and Indonesia. The Actros MP4 / Antos / Arocs platform is one of the most common Bosch 0445 service applications across this customer base. Reference cases and test reports are available on request through WhatsApp or email below.

For more information on the EPS205, EPS211 or CR217 with the Bosch 0445 Actros MP4 / Antos / Arocs test plan pre-loaded, contact the BEACON MACHINE team. We configure the bench, run the acceptance test on a sample 0445 injector, and ship it ready to use. CIF shipping to your nearest port is arranged on request.