How much does it cost to replace OM651 injectors?

A set of four remanufactured OM651 injectors typically costs between £400-£600. Labour is approximately 2-3 hours at most garages. Total cost including fitting ranges from £600-£900.

Can I drive with a faulty OM651 injector?

We advise against it. A leaking injector can wash the cylinder bore, damaging piston rings and causing oil dilution. It can also damage the catalytic converter or DPF.

Do OM651 injectors need coding after replacement?

Yes. Each injector has a unique calibration code that must be programmed into the ECU using Mercedes Star Diagnostic or compatible software.

What is the OM651 injector torque setting?

The injector clamp bolt should be torqued to 7 Nm. Over-tightening can crack the injector body or damage threads in the cylinder head.

How much does it cost to replace injectors?

Replacement typically costs £150–£350 per injector depending on brand and engine. A full set of four with professional fitting usually costs £600–£1,200.

Can I drive with a faulty injector?

Driving with a faulty injector can cause engine damage, increased fuel consumption, DPF contamination, and oil dilution. We recommend diagnosis and replacement as soon as possible.

Do new injectors need coding?

Some vehicles require injector coding after replacement using manufacturer-specific diagnostic tools. Many Bosch solenoid units are plug and play. Check your engine guide for specific requirements.

Why is my diesel injector knocking?

Diesel injector knocking is typically caused by worn nozzle tips that alter the fuel spray pattern, leading to harsher combustion. Carbon buildup, incorrect injection timing, and high fuel pressure can also contribute. A professional leak-off test can confirm whether injectors are the cause.

Can a bad injector cause white smoke?

Yes. A faulty injector that dribbles fuel instead of atomising it causes incomplete combustion, producing white or grey smoke. This is especially noticeable on cold starts and typically clears as the engine warms up.

How long do diesel injectors last?

Most diesel injectors last between 80,000 and 150,000 miles depending on fuel quality, driving conditions, and maintenance. Regular fuel filter changes and using quality diesel can extend their lifespan.

Will injector cleaner fix misfire?

Injector cleaner may help with minor carbon deposits, but it cannot fix worn nozzles, failed solenoids, or internal seal leaks. If misfire persists after using cleaner, professional testing and likely replacement is needed.

Mercedes OM651 Injector Problems: Symptoms, Fault Codes & Repair Costs (UK)

Updated for 2026 diagnostics & repair guidance

Common failure compared to BMW N47 & VW 1.6 TDI injector faults.

The OM651 diesel engine is widely used in the Mercedes-Benz C-Class, E-Class, Sprinter, and Vito. Over time, fuel injectors may develop faults that affect performance, starting, and emissions. This guide helps you diagnose injector issues and determine when replacement is required.

OEM tested & calibrated12-month warrantyFree UK deliveryNo coding required (most models)

Drivers also ask

Quick Diagnosis

If your OM651 engine shows:

rough idle
hard starting
white or black smoke
knocking or ticking noise
reduced fuel economy

A faulty injector may be the cause. Continue below to confirm symptoms and solutions.

Can You Drive With This Problem?

Driving short distances may be possible, but continued use can cause:

piston damage
turbo contamination
fuel dilution of engine oil
catalytic converter damage

Prolonged driving may lead to major engine failure.

Typical Repair Costs (UK)

Average costs for injector-related repairs:

£180 - £350

Per Injector

£700 - £1,200

Full Set (4)

£120 - £300

Labour

Early replacement prevents costly engine damage.

Common Injector Failure Symptoms

Owners frequently report:

Rough idle and engine vibration

The OM651 commonly develops a lumpy idle due to injector seal leaks allowing combustion gases into the fuel return. This causes uneven fuel delivery across cylinders.

Black smoke under acceleration

Worn injector nozzles over-fuel one or more cylinders, producing visible black smoke. Most noticeable when pulling away or climbing hills.

Engine management light (EML)

Fault codes P0201-P0204 (injector circuit faults) or P2146/P2149 (fuel injector group faults) stored in the ECU.

Diesel knock at cold start

A distinct knocking sound on cold starts that fades as the engine warms indicates injector timing drift or worn nozzles.

Poor fuel economy

Leaking or dribbling injectors waste fuel, dropping MPG by 10-20% compared to when the engine was new.

Full symptom guide White smoke guide

Fault Codes Linked to Injector Issues

Common diagnostic codes include:

P0201-P0204Injector circuit malfunction (cylinders 1-4)

P2146Fuel injector group A supply voltage circuit open

P2149Fuel injector group B supply voltage circuit open

P0087Fuel rail system pressure too low

P0093Fuel system leak detected (large)

Misfire diagnosis guide

How to Diagnose OM651 Injector Faults

Follow this step-by-step testing approach to identify the faulty injector:

1
Read fault codes
Connect an OBD-II scanner and note any injector-related codes (P0201–P0204, P2146, P2149). This identifies which cylinder is affected.
2
Perform a leak-off test
Disconnect the fuel return pipes and route into measuring containers. Run the engine at idle for 60 seconds. Compare volumes per cylinder against manufacturer spec.
3
Listen for injector tick
Use a mechanic's stethoscope on each injector body. A dead or irregular tick indicates a stuck or failing solenoid.
4
Check fuel rail pressure
Monitor live fuel rail pressure data via diagnostic tool. Low pressure can mimic injector symptoms and may indicate a fuel pump issue instead.
5
Inspect for external leaks
Check around injector seals for signs of fuel or combustion gas leakage. Black carbon deposits indicate a blown seal.
6
Cylinder balance test
Use diagnostic software to run a cylinder contribution test. This electronically disables each injector in turn to measure its effect on engine speed.

Full leak-off test guide Injector coding guide

Why OM651 Injectors Fail

Common causes include:

fuel contamination
high-pressure wear cycles
carbon buildup
poor fuel quality
internal valve wear

Professional remanufacturing restores spray pattern and pressure accuracy.

When Replacement Is Required

Injector replacement is recommended if:

leak-off test fails
misfire persists after coding
excessive return flow detected
spray pattern fails testing
vehicle enters limp mode

OM651 Repair Advice

Always replace injector sealing components when fitting new injectors. The OM651 requires injector coding via Star Diagnostic or compatible OBD tool after replacement. Torque injector clamp bolts to 7 Nm. We recommend replacing all four injectors simultaneously for balanced performance.

Remanufactured (Recommended)

OEM-spec rebuild with new nozzles, seals, and solenoids. Full flow testing. 12-month warranty. 40–60% less than new.

Brand New OEM

Factory-fresh from Bosch, Delphi, or Siemens. Highest cost but zero previous wear. Best for low-mileage vehicles.

Vehicles Using the OM651 Engine

This engine is commonly found in:

Mercedes-Benz C220 CDI

W204 · 2008-2014

Mercedes-Benz C250 CDI

W204 · 2008-2014

Mercedes-Benz E220 CDI

W212 · 2009-2016

Mercedes-Benz E250 CDI

W212 · 2009-2016

Mercedes-Benz Sprinter 313 CDI

W906 · 2009-2018

Mercedes-Benz Vito 113 CDI

W639 · 2010-2014

Mercedes-Benz GLC 220d

X253 · 2015-2019

Professional Installation Tip

Always:

replace copper sealing washers
torque injectors to manufacturer specification
clean injector seats before installation
code injectors after installation (if required)

Leak-off test guide Injector coding guide

Compatible Injector Part Numbers for OM651

The following injector part numbers are commonly associated with OM651 engines:

Bosch

0445110351

Bosch CRIN3 injector for OM651 (most common)

View details

Bosch

0445110299

Bosch injector for early OM651 variants

View details

Bosch

0445117034

Bosch piezo injector for late OM651 applications

View details

Mercedes-Benz

A6510700587

Mercedes OE reference number

View details

OM651 Injectors — Shop Now

In-stock injectors listed first for fastest delivery:

MERCEDES C CLASS ( C220 CDI CLASSIC SE A 203) 2.2L 2003-2004 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE 203) 2.2L 2003-2004 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE AUTO 203) 2.2L 2000-2002 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE SE A 203) 2.2L 2003-2004 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI SE S-A 203) 2.2L 2003-2004 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE A 203) 2.2L 2003-2003 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE S-A 203) 2.2L 2003-2003 Diesel Injector

£150.00

In StockNext-day delivery12 months

MERCEDES C CLASS ( C220 CDI ELEGANCE SE 203) 2.2L 2003-2004 Diesel Injector

£150.00

In StockNext-day delivery12 months

View all OM651 injectors

These injectors are commonly used with the OM651 engine. Confirm compatibility using your engine code or registration lookup before ordering. Our team can verify the correct part for your specific vehicle.