Injectors And Fuel Economy

[Billysbones]

The Car:
2010 Rav4.3 2.2l diesel.

The Problem:
A couple of weeks ago, whilst on holiday (and towing a caravan) I got an engine managment light on the OBC. It was flashing between the generic "Check engine" and "Check 4x4 system" alarms. (May not have got the wording spot on there, but you get the gist)
Anyway, booked it in at to a local Dealer the next morning, by which time to alarms had cleared and no faults showing, but the they put it on the diagnostics to read the fault codes.
They told me that the code showed an injector fault, and as it had cleared, I shouldn't worry, as it may never show itself again. He also told me that should it appear again, I may need to change all the injectors (costing £1600 - £2000), as the "step 1" injectors are no longer available and would have to upgrade to step 2 injectors.
I drove off hoping I never see the alarm again, and was just a one off, although I still don't see why the 4x4 alarm would show for an injector fault.

Have been back off me hols for a couple of weeks now, and it seems that the diesel usage is high. Previously with careful-ish driving, I would be getting 45 MPG, but at present am getting 35 -38 MPG. I am assuming the two are connected.
Have the forum members any wisdom on such matters? I did read something about getting them chipped to improve MPG, which I have half considered in the past, but this seems to be a drop in previous performance.
There doesn't seem to be any other symptoms, like sluggish power delivery or excessive smoke.

Any help appreciated.

[Avalon]

If it's got an underlying issue mapping it will not help. It could be worth having your existing injector stripped/tested/cleaned and refurbed? Also it's only 5 years old so i'm assuming just out of warranty, surely they're offering a decent contribution towards this?

Just to add Techstream allows you to monitor injector figures, for example one of my injectors is noticeably out of spec compared to the other 3.