Stevie135 · Dec 27, 2023

Hi All, hope the festive season continues well!

It would be perfect for me if only I could diagnose my D4 issue! I'm getting the fault shown above pretty much every time I drive it! This first happened on a long trip (Liverpool to Brighton) that I was doing in a single day. No hard drive just motorway cruising at circa 70mph... ran great on the way down but 80 odd miles into the return I got the fault light and reduced power. a stop at the services and 5 mins downtime and all was good for the rest of the journey and indeed the next week or so of pottering around. Since then its got more regular until its literally every trip.
The only thing I'd done before the first occurrence was an oil change using a vac system and disconnecting/flushing the coolant circuit that runs to the interior heater matrix (to no avail but that another story!).
I've replaced the MAF on bank 1 (not an LR original but a new spare from a popular motor factors) - same issues,
swapped to bank 2 - same issue
removed new sensor and swapped originals place wise - no change - exactly the same fault code.

When I check the code its showing as either pending or intermittent state - other than this little info. I have fault data from a few occurrences but this doesnt seem to indicate anything (at least according to JustAnswer...). I've tried to do a smoke test and struggled a bit but nothing obvious at this stage - I need to try again. Did notice some oil on top of the engine on the right hand side when doing this - not much but its in the foam on the underside of the plastic cover and on top of some sort of housing connected to a pipe that runs to the radiator... Connected maybe? Or sloppy work when replacing filter possibly as they are close by....

So my question is this - is there anything specific in the event data I should look for (I've tried to attached a PDF of one such event)? Any tips, tricks or help would be greatly appreciated! I would take it to a professional but thats 4 to 6 weeks away looking at availability and I'm worried about driving it in the mean time but of course need it for every day.

Many thanks for any advice and all the best for 2024!

Regards

Steve

sierrafery · Dec 27, 2023

Hi, replacing the MAF would not help much for this code, here's the guide for it from the WSM:

Stevie135 · Dec 27, 2023

Ah thank you! Ok some more probably a leak then and back to finding a reliable way of getting smoke into the inlet without my neighbours calling the fire brigade

Lazydave · Dec 27, 2023

Spray soapy water on inlet manifolds whilst someone is revving the engine. Sounds like a possible cracked inlet manifold as the issue is slowly getting worse.

Cipher · Dec 28, 2023

Stevie135 said:
Hi All, hope the festive season continues well!

It would be perfect for me if only I could diagnose my D4 issue! I'm getting the fault shown above pretty much every time I drive it! This first happened on a long trip (Liverpool to Brighton) that I was doing in a single day. No hard drive just motorway cruising at circa 70mph... ran great on the way down but 80 odd miles into the return I got the fault light and reduced power. a stop at the services and 5 mins downtime and all was good for the rest of the journey and indeed the next week or so of pottering around. Since then its got more regular until its literally every trip.
The only thing I'd done before the first occurrence was an oil change using a vac system and disconnecting/flushing the coolant circuit that runs to the interior heater matrix (to no avail but that another story!).
I've replaced the MAF on bank 1 (not an LR original but a new spare from a popular motor factors) - same issues,
swapped to bank 2 - same issue
removed new sensor and swapped originals place wise - no change - exactly the same fault code.

When I check the code its showing as either pending or intermittent state - other than this little info. I have fault data from a few occurrences but this doesnt seem to indicate anything (at least according to JustAnswer...). I've tried to do a smoke test and struggled a bit but nothing obvious at this stage - I need to try again. Did notice some oil on top of the engine on the right hand side when doing this - not much but its in the foam on the underside of the plastic cover and on top of some sort of housing connected to a pipe that runs to the radiator... Connected maybe? Or sloppy work when replacing filter possibly as they are close by....

So my question is this - is there anything specific in the event data I should look for (I've tried to attached a PDF of one such event)? Any tips, tricks or help would be greatly appreciated! I would take it to a professional but thats 4 to 6 weeks away looking at availability and I'm worried about driving it in the mean time but of course need it for every day.

Many thanks for any advice and all the best for 2024!

Regards

Steve

Hi Steve
This does sound very much like an air leak somewhere, recheck all intake related hoses, check them carefully squeeze and massage them between your fingers and see if there are any cracks that appear, also check turbo hoses in the same manner, and listen (while the engine is running) for hissing noises especially when you 'blip' the throttle. also you mention changing a filter, I assume an air filter, make sure all pipes are refitted correctly and not partially dislodged and all hose clamps are tight..
Also as a side note you mention changing the oil and later found a small amount of oil, check that any plastic housings or manifolds are not cracked, plastics in modern day cars get super brittle as they age and can crack very easily
Hope that helps

Stevie135 · Dec 31, 2023

Cipher said:
Hi Steve
This does sound very much like an air leak somewhere, recheck all intake related hoses, check them carefully squeeze and massage them between your fingers and see if there are any cracks that appear, also check turbo hoses in the same manner, and listen (while the engine is running) for hissing noises especially when you 'blip' the throttle. also you mention changing a filter, I assume an air filter, make sure all pipes are refitted correctly and not partially dislodged and all hose clamps are tight..
Also as a side note you mention changing the oil and later found a small amount of oil, check that any plastic housings or manifolds are not cracked, plastics in modern day cars get super brittle as they age and can crack very easily
Hope that helps

Thanks for this going to do some diagnosis today. Actually had the engine light come on with the fault recently too… this requires resetting with a diagnostic device and won’t reset with a restart as the fault light does. Hoping that there’s some additional fault codes in there to aid the diagnosis!

Stevie135 · Dec 31, 2023

OK - really confused now... cant find any leak. Cant here or see anything with leak detector spray. The engine management light had actually reset itself over night too. So just driven for 40 mins at various speeds etc and light wont come on... its never done this before and I'm scratching my head. I think if it keeps happening it will be in to the nearest LR service centre for a qualified tech to take a look for me :-(

sierrafery · Dec 31, 2023

Miht be a leak which occurs only under load

Stevie135 · Dec 31, 2023

sierrafery said:
Miht be a leak which occurs only under load

Hmm I think you may be right! I tried to forget my frustration and repeat the test in a more structured manner with engine at a set revs of between 1 and 2 k (previously it had been revved up and down etc). In the picture the area circled in blue - would that be turbo intake perhaps? im getting spluttering and pooling of the leak detection spray going in the direction of the yellow arrow in that approximate area and you can see evidence of oil too.... I tak it this isnt normal? Please could you advise what this area is?

Many thanks

Steve

sierrafery · Dec 31, 2023

Unfortunately i have no personal experience with this kind of engine, my replies were generical but as long as it's a leak there you must fix it without doubt.

Stevie135 · Dec 31, 2023

sierrafery said:
Unfortunately i have no personal experience with this kind of engine, my replies were generical but as long as it's a leak there you must fix it without doubt.

Many thanks for the advice! All the best for 2024

Cipher · Dec 31, 2023

Hi, Steve the picture was as great help, I/we can see exactly whats going on, in the first instance I'd definitely be trying to sort out that oil leak that you have on the N/S bank, and I think I'm correct in that where the oil leak you have found is part of the induction system there is oil mist that swirls around in there and that's why you can see oil, the steel plate that is fastened to the cover is secured by plastic posts that stick up, and if you've caught one of these it could well have cracked the cover, these covers are notorious for becoming brittle and cracking and it's a known fault and ideally they need replacing, big job tho, some people use an epoxy resin/glue to repair the crack, (don't know how effective that is). If fixing that doesn't cure it then it could be a throttle body housing issue, (that would be my next port of call) here is a link to a you tube video of how to check one with full explanation, (as a newbie here will the moderator step in for posting YT links? hope not)

Hope this helps
Happy New Year...

Stevie135 · Dec 31, 2023

Cipher said:
Hi, Steve the picture was as great help, I/we can see exactly whats going on, in the first instance I'd definitely be trying to sort out that oil leak that you have on the N/S bank, and I think I'm correct in that where the oil leak you have found is part of the induction system there is oil mist that swirls around in there and that's why you can see oil, the steel plate that is fastened to the cover is secured by plastic posts that stick up, and if you've caught one of these it could well have cracked the cover, these covers are notorious for becoming brittle and cracking and it's a known fault and ideally they need replacing, big job tho, some people use an epoxy resin/glue to repair the crack, (don't know how effective that is). If fixing that doesn't cure it then it could be a throttle body housing issue, (that would be my next port of call) here is a link to a you tube video of how to check one with full explanation, (as a newbie here will the moderator step in for posting YT links? hope not)

Hope this helps
Happy New Year...

This is awesome thank you! All the best

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