Replacing diesel injectors

Question

Two weeks ago, I purchased a 9 year old, second hand Ford Fiesta from a UK used car dealership. It's done 58,000 miles, has a full service history and has had a recent MOT.

After the first week, one of the diesel injectors failed. The dealership agreed to repair this. One week on, a second diesel injector has failed and my mechanic has also spotted corroded surfaces on the front brake pads.

I have spoken to the dealership and they have said they cannot offer a refund, but instead pay for the repairs on the second failing injector and brake pads. They are also trying to shift blame on my mechanic for the second injector failing.

Is it likely that further injectors will fail with the second being replaced or is too difficult to say? I would prefer to have all of them done to ensure I don't break down for a third time.

Answer 1

Replacing one injector wont make another fail, but it's worth remembering all four fire the same amount of times and are all the same age so wear the same amount.

However I wouldn't needlessly replace all of them, to reliably test the remaining two injectors you need to do a leak-off test and current measurement of the injectors with a oscilloscope.

The leak off test just measures how much excess fuel is returned from the injector, all four should be within 10% and then compared against a known good reference value.

Another often overlooked test is to measure the current using a current clamp with a oscilloscope, this not only confirms the fault is in-fact with the injector and not the wiring or ECU but a good 'scope user can gain loads off info about the injector characteristics and how the needle is moving inside.

To be fair I would say the garage is being quite fair apart from saying the mechanic damaged the second injector which doesn't seem possible. You cant expect them to replace something that isn't broken.