The OM611 2.2‑litre CDI engine is a workhorse, but injector failure is a common and expensive issue. This guide covers what to look for, what it costs to fix in 2026, and whether it's a write‑off.
OM611 injector failure is a common diesel issue that typically appears between 80,000 and 120,000 miles. Repair is usually cost‑effective, but catching it early is key.
Full symptom progression, root cause, affected models and cost breakdown below.
OM611 injector failure rarely happens overnight. These are the stages owners consistently report — if you're at stage 2, act quickly.
If you notice rough running or black smoke, do not ignore it. A simple injector leak‑off test can confirm the issue before it becomes a £2,000+ engine rebuild. See our black smoke guide for more context.
The OM611 uses a common‑rail fuel injection system with solenoid‑controlled injectors. Each injector contains a precision‑machined nozzle, a solenoid, and a control valve. Over time, several things can go wrong.
The most common failure is wear on the injector nozzle, which can cause poor atomisation, leading to incomplete combustion, black smoke, and rough running. The solenoid can also fail electrically, causing the injector to stick open or closed. Another common issue is contamination from poor‑quality diesel or water in the fuel, which can damage the delicate internal components. Finally, the injector seals can leak, allowing combustion gases to escape and causing a "chuffing" noise and loss of compression [PATTERN DATA].
Unlike some later engines, the OM611 injectors are relatively simple to replace, but precise calibration is required. For a deeper dive into the OM611 platform, see our OM611/OM613 Knowledge Centre.
| Model | Chassis | Years | Risk Level |
|---|---|---|---|
| C‑Class (W203) | W203 / S203 | 2000–2007 | High — very common |
| E‑Class (W210) | W210 / S210 | 1996–2002 | Very common |
| E‑Class (W211) | W211 / S211 | 2002–2009 | Common in early models |
| Sprinter (W901‑905) | W901‑905 | 1995–2006 | High — very common in vans |
| Vito (W638) | W638 | 1996–2003 | Documented |
| CLK (C208) | C208 / A208 | 1998–2002 | Less common |
The OM611 is a 2.2‑litre inline‑4 diesel used in many Mercedes models of the late 1990s and early 2000s. Always verify your engine code before assuming you have this issue. For full chassis‑specific detail, see our fitment matrix.
Low‑quality diesel or contaminated fuel can clog injector nozzles and damage the solenoid, leading to premature failure.
A clogged fuel filter restricts flow and can allow debris to reach the injectors, causing wear and blockages.
Injectors are wear items. After 100,000 miles, the internal components are more likely to suffer from wear and tear.
Using a Mercedes‑compatible diagnostic tool, a specialist reads fault codes from the engine ECU. Common codes include P0200 (injector circuit) and P1200 (injector calibration).
This measures the amount of fuel returning from each injector. Excessive leak‑off indicates a faulty injector that needs replacement.
In some cases, injectors are removed and tested on a bench to check spray pattern, flow rate, and electrical response.
If you're experiencing symptoms, our Diagnostic Wizard can help narrow it down.
The cost of fixing OM611 injectors varies. Early diagnosis is significantly cheaper.
| Stage | Recon S&F (Indie) | Used S&F (Indie) | Main Dealer Est. |
|---|---|---|---|
| Single injector replacement | £200–£400 | £150–£300 | £500–£800 |
| Full set of 4 injectors | £600–£1,200 | £500–£900 | £1,500–£2,500 |
| Injector failure causing engine damage | £2,000–£4,000+ | £1,500–£3,500 | £4,000–£7,000 |
Labour estimates: injector replacement is 2–3 hours per injector; a full set is 4–6 hours. Prices are indicative for 2026; always obtain a written quote for your specific vehicle. Tags: [INDUSTRY ESTIMATE].
OM611 injectors are durable, but you can significantly extend their life with good maintenance.
For a deeper discussion of repair‑vs‑replace economics on the OM611 platform, see our Repair vs Replace vs Scrap Framework.
⚠️ Watch — but often worthwhile.
Our data flags OM611 injector repair as Watch against the 70% threshold on some very low‑value examples [EM-VERIFIED]. On most C‑Class, E‑Class and Sprinter models, a single injector replacement is well within the value of the car. However, on a very low‑value example (sub‑£1,500), a full set replacement could exceed 70% of the car's worth. Always obtain a current valuation and a firm quote. For most owners, fixing the injector is a sensible investment. See the full economics framework for a worked example.
If you're still uncertain, compare this failure to the OM646 injector seal failure or read real owner decisions in our case studies section.
The earliest signs are rough idle, black smoke from the exhaust, and a noticeable loss of power. You may also experience increased fuel consumption and a check engine light.
In the early stages, you can drive the car to a specialist for diagnosis. However, if the injector is stuck open, it can cause cylinder wash and severe engine damage. If you notice persistent rough running or excessive smoke, stop driving immediately.
For a single reconditioned injector supply and fit, expect £200–£400 at an independent specialist. A full set of four typically costs £600–£1,200. Main dealer prices are significantly higher, often £500–£800 per injector.
It depends on the vehicle's value. On most C‑Class, E‑Class and Sprinter models, a single injector replacement is well worth it. However, on a very low‑value car (sub‑£1,500), a full set replacement may approach or exceed 70% of the car's value. Use our repair‑vs‑replace calculator to help decide.
Mercedes has issued several technical service bulletins (TSBs) related to injector issues on OM611 engines, but there has been no full recall. Some early OM611 engines (1999–2001) had injector wiring harness issues that were covered under warranty extensions in certain markets. Check with your dealer using your VIN to see if any campaigns apply to your vehicle.
Failure typically occurs between 80,000 and 120,000 miles. Engines with poor fuel quality or neglected maintenance can fail much earlier, while well‑maintained engines may exceed 150,000 miles without issue.
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