varooom

It might be best to get it back to the place that replaced the injector, as warranty lies with them. I assume they plugged in diagnostic tool to verify and fit replacement part? My gut says you have a broken wire in the loom, and what was a temporary issue is now permanent. When the car originally faulted and went into limp mode, did it run really rough? Might be an idea to expand original symptoms of when the fault occured, what you did after (stop engine and restart?)

I am no expert by a long stretch, but odds are you have a break in the wiring loom that is intermittant. Could now be more permanent shall we say. Has the fault code changed, or is it same. Also if you have a multimeter, you could be checking Inj 4 values vs the other injectors (are you getting Voltage on a wire that you shouldn't be now, or a loss of Voltage?)

Had a fair look at wiring, cannot see the colour combo you describe. Unless someone has other ideas, a picture when near the car would help. 2-pin connector, where pin 1 should be a negative, so should be easier to locate which of the 2 wires goes where (I would hope)

Glad you edited, the part has been replaced several times 04L 906 088 -> 04L 906 088 AE -> 04L 906 088 DQ -> 04L 906 088 HT Have you got image for your replacement plug wiring?

From memory, there should be a series of numbers on the side of most injectors, a calibration value. This needs inputting into the car to avoid under/over fuelling. Got printout of fault codes in the car? Never assume a faultcode is gospel, could be issue in fuelling system causing error.

You need to look to see what location exactly to confirm your temp sensor is going to, as you have positions 3 & 8 both pre-turbo. Can you get a picture of the current replacement sensor, and it would be helpful to see the wires on that. Part number if printed on it (should be)

That is a snippet from the Maintenance document for your car. You can buy all the supporting documents from erWin, repairs/maintenance/wiring diagrams. Handy purchase if you plan to keep the car for a few years, and not that expensive for 1hr access.

Potentially you are looking at MU SW 1760 I need to unpack and check the supported SW Train seen in image is on the "list"

Sadly not seen anything in the documents like this either, barely anything on this. I did find that your cap has several choices, so it appears you can swap the smaller black item depending on filter used. https://www.autodoc.co.uk/quinton-hazell/18414767 My only assumption is the spring is to make sure the filter presses down on the filter via the smaller black part fitted, and that the spring goes in the black cap itself. Bit like yesterday, you may have to wait for the help to arrive, where someone has fitted these before and can let you know.

If you flip over the left oil cap, the spring should fit in the bottom, then the small black part fit in, showing the silver spring part inside it visible towards you? Best guess Does yours look like this when flipped? The Spring and black part are not exploded in this image, but should be able to fit together

Look at the picture above, quotes Software Train, it also has the firmware update button (needed) Hold Menu key down and provide details.

Car nil Human one

I'm overdue an eye test. It's on the label file VCDS uses 😄

I think Tesla and BMW are turning your car into a cash cow, so you either pay for features one time, or a monthly fee for some things. Example BMW heated seats or steering wheel being an extra. Not a big fan, and totally agree with you that it should really be switched on, but greed gets in the way of that.

After Dieselgate, they are going to claw back as much as possible though 🤔 Happening across the range, so many extras are getting cut, even if it's dirt cheap to fit. Bean counters strike again.

A sticker with 3/4 characters Could be in the boot under the floor mat Sometimes printed on owner book Can even be in a door jamb

@Jamie_B I don't suppose you know your engine code for your car?

Bonnet

That was my fear, rounding off the plug. Best to increase torque gently. 2 choices, try again with extended torque, or await for help.

Did you try a spanner on the end of ratchet to increase the torque? Only say as one young mechanic I watched was trying to undo a top mount, and failing, told him to increase torque by extending the length. If you do try this, don't go wrenching it, try to apply it steadily.

What tool was you using to undo?

0369 is available for this Software Train

We could do with an update from the OP as to the possible outcomes.

It doesn't mention anything specific for Kessy

I would have followed @ApertureS advice and paid the fee extra pounds for the information, and you could have gotten wiring diagrams and repair information etc. I would have posted this earlier, but had to go out.