Mercedes OM654 Injector Problems: Symptoms & Replacement Guide (UK)

The OM654 replaced the OM651 as Mercedes' primary 4-cylinder diesel. It features aluminium construction, stepped-bowl pistons, and a new Nanoslide cylinder coating. Injector issues are less common than the OM651 but emerge at higher mileage.

Common OM654 injector failure symptoms

• Subtle idle roughness: The OM654 is extremely refined — even minor injector deviation produces noticeable roughness compared to normal.
• AdBlue warning alongside injector codes: Poor combustion increases NOx, triggering SCR warnings that can mask the underlying injector fault.
• DPF regeneration frequency increase: Worn injectors increase soot production, causing more frequent DPF regeneration events.
• Cold start hesitation: Injectors that fail to atomise correctly during pilot injection cause brief cranking hesitation.

Why OM654 injectors fail

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

How to diagnose OM654 injector faults

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.

Fault codes linked to OM654 injector issues

• P0201-P0204 – Injector circuit malfunction
• P2002 – DPF efficiency below threshold (secondary symptom)
• P20EE – SCR NOx catalyst efficiency below threshold

OM654 repair advice

The OM654 requires IMA coding via Star Diagnostic after injector replacement. The aluminium cylinder head requires careful torque control.

OM654 injector replacement cost (UK)

• Per injector: £180 - £350
• Full set: £700 - £1,200
• Labour: £120 - £300

Compatible injector part numbers for OM654

• Bosch 0445110571 – Bosch solenoid injector for OM654
• Mercedes-Benz A6540700100 – Mercedes OE reference

Vehicles using the OM654 engine

• Mercedes-Benz C220d (2016-2021)
• Mercedes-Benz E220d (2016-2021)
• Mercedes-Benz GLC 220d (2019-2022)
• Mercedes-Benz Sprinter 314 CDI (2018-present)

Find your exact OM654 injector by registration

Frequently asked questions

Are OM654 injector problems common?

Less common than the OM651 due to the newer design. Most issues appear after 80,000+ miles.

How much does OM654 injector replacement cost?

A single remanufactured injector costs £250-£400. Labour is 2-3 hours. Full set: £1,000-£1,600 plus labour.

Do OM654 injectors need coding?

Yes. IMA coding via Star Diagnostic or compatible tool is mandatory.

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.