Mercedes BlueEfficiency (OM651) – Injector Problems

Mercedes seem to have big issues with the injectors on the OM651 Engine

Update: There has been a lot of interest in this article, and we’ve asked Mercedes a number of questions about the injector issue. They haven’t answered, but you may find the article on Mercedes Injector Problems – the unanswered questions useful.

Cars UK isn’t exactly Watchdog. But when we get a number of comments on the site about problems with a car – and far more emails on the same subject – we tend to sit up and take notice. And that’s where we find ourselves with injector problems on the latest Mercedes BlueEfficiency C-Class and E-Class.

We reported back in June last year on the new engines for the C Class BlueEfficiency and said how impressive the figures where. More economical, more powerful and less polluting, they seemed to be another example of how car makers are managing the Holy Grail of more for less with each generation of car.

And we had no hesitation in calling the C Class BlueEfficiency a good buy. Mercedes has once more become a car maker to rely on after a decade of chasing profits at the expense of quality. Pre 1995 Mercedes were bullet proof. I ran consecutive S500s and they didn’t miss a heartbeat in a combined 500k miles (well, one lambda probe). And we’d come to the conclusion that Mercedes were now back to where they always were, as makers of extremely desirable, reliable and well-made cars.

So it’s sad to see that there is a real problem with the Mercedes BlueEfficiency (OM651). It takes no time at all to undo a hard-won reputation (as Mercedes have already found out once to their cost) and, despite Mercedes’ assurance that they are addressing this problem, Cars UK readers are not convinced. So what do Mercedes say? We asked them for a statement and received the following:

“A problem has been identified which is due the manufacture of a small number of faulty diesel fuel injectors by our supplier, which can affect 220 CDI and 250 CDI models of the C-Class and E-Class ranges fitted with the new OM651 engine.

“The problem can manifest itself in a number of ways from illumination of the engine warning light; uneven engine running characteristics; or in the worst case, the car entering its “limp home” mode. In “limp home” mode the car remains driveable albeit at a lower speed than in normal use.

“As an interim solution, Mercedes-Benz has provided a loan car to the small number of customers affected by more than one failure, and will return the customer’s vehicle once repaired and fully tested by its technical team. This is in addition to the offer of a £250 Mercedes-Benz voucher, or a complimentary first service to each of these customers.

“We are working hard with our supplier to ensure provision of sufficient parts so we can replace all the injectors in affected cars, at once. Mercedes-Benz is committed to excellent levels of customer service and takes its responsibilities very seriously.”

Which seems commendable and it looks as if the problem is minor and affecting just a small number of cars. But is it? Perhaps in terms of percentage, but it would appear the problem is bigger than Mercedes seem to be admitting. We had one email which told us that when one reader’s C220 broke down with injector problems he was told he would have to wait for parts until the 30 cars at his dealership with the same issues had received their parts. Another reader told us that when his car broke down the mechanic who turned up from Mercedes Assist told him his was the fourth car he’d attended with faulty injectors in the last 24 hours.

It would seem the big issue is with parts sourcing. Mercedes use Delphi to supply the injectors and it seems they are unable to source sufficient parts to resolve the issues, with many of our readers reporting their cars off the road for months. True, Mercedes do seem to be offering loan cars to owners who have had more than one injector failure (surely they should be doing it for everyone?). But one reader told us Mercedes supplied him with a VW as a loan car. Are there that many issues with injectors that Mercedes don’t have enough loan cars to go round?

We’re sure Mercedes are doing what they can to resolve this. It is difficult when the parts you need are coming from an outside supplier, but that’s not the customer’s fault or problem. It’s Mercedes’. They can’t conjure injectors out of thin air, but they need to keep their customers better informed. They also need to be giving – even if they have to rent them – a loan car to every customer with this issue.

Mercedes has probably already lost a number of customers over this issue. If they’re not seen to be bending over backwards to help those customers affected they’re in danger of losing not just customers but their reputation – all over again.

And that would be sad.

By Cars UK