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911r44



Member Since: 30 Oct 2022
Location: Nottingham
Posts: 10

United Kingdom 
Twitchy body

Hi folks

Has anyone experienced an L405 body twitching? Feels like the car lifts up and then down a couple of cms on one corner. It's too fast to be the air suspension, must be the ACE system.


I scanned the car and found this fault - c1049-63 front axle rod pressure regulating valve

Is this a symptom of the valve block? It's a 2013 car, probably still got the original installed. Anyone changed one.....how hard is it? If necessary, I'll get a used later version from a breakers and replace it.

As always, thoughts and experiences much appreciated.

Post #721010 8th Jul 2025 10:25am
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fisha



Member Since: 25 Sep 2009
Location: Scotland
Posts: 1511

2015 Range Rover Autobiography SDV8 Aruba

I don't see a C1049-63 error code in the manual, only these 2:

C1049-62 Front Axle Rod Pressure Regulating Valve - Signal compare failure
C1049-64 Front Axle Rod Pressure Regulating Valve – Signal plausibility failure

Which in a little more detail:

C1049-62 Front Axle Rod Pressure Regulating Valve - Signal compare failure

    - Dynamic response hydraulic fluid circuit requires bleeding
    - Dynamic response hydraulic fluid low
    - Dynamic response hydraulic fluid leak from high front axle rod pressure primary circuit, secondary circuit or dynamic response hydraulic fluid reservoir
    - Dynamic response hydraulic fluid contaminated Broken stabilisation link
    - Broken roll bar module
    - Sensor fault
    - Valve fault - Sticking valve
    - Actuator fault
    - Dynamic response hydraulic fluid reservoir suction port screen damaged


There is some suggestions around steps to take / try ... but I think first and foremost, check the simple things.

a - is there fluid in the reservoir ?
b - are you sure you dont have a leak ?

There are a number of threads on the ACE system, the fluid, the pipes which corrode ( particularly at that age ) and their replacement.

I'm not a betting man, however, my first instinct gut thought is that you have a leak or blocked filter, that the fluid has dropped to a level where the pump is scavenging fluid or similar, and rather than being able to maintain a flow at a set pressure, its grabbing what fluid it can and pumping it, then running short and so the flow is stuttering, and what you're seeing as a result is that stuttering flow transferring into the hydraulic roll bars.


- or -

if you do have fluid and no leaks

I've found that mud and crud gets thrown up off the front wheel and lies on top of the valve block where the electrical connectors are. Might be worth taking the under sill off and making sure that the top of the valve block is all clear of crap, and that the connectors are all in good order. thats an easy thing to do. V8 or else ...

Post #721049 8th Jul 2025 11:26pm
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911r44



Member Since: 30 Oct 2022
Location: Nottingham
Posts: 10

United Kingdom 

Thank you fisha

I have fluid in the reservoir and there are no leaks. I will certainly follow your advice and look at the block and connections.

The car only seems to twitch when it's cold, after driving for 10 mins or so it stops. I wonder if the oil temperature has something to do with it.....could well point to a filter somewhere.....

Will keep you posted

Post #721056 9th Jul 2025 8:07am
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fisha



Member Since: 25 Sep 2009
Location: Scotland
Posts: 1511

2015 Range Rover Autobiography SDV8 Aruba

The fluid tank is viewed as a serviceable item because of its filter … can’t remember the mileage to change it at though. 80k miles rings a bell. V8 or else ...

Post #721060 9th Jul 2025 10:36am
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911r44



Member Since: 30 Oct 2022
Location: Nottingham
Posts: 10

United Kingdom 

An update regarding the active roll issue.

Having read lots and lots of threads, it seems uncommanded body roll is not that uncommon. People have mentioned replacing various components but ultimately it seems like it's a valve block issue.

My car (2013) has the original CPLA type block fitted, it has not been replaced by the FLPA type.

I ran some diagnostics using GAP, trying to see what was moving and why, was it commanded electronically (ie, control module fault) or is it the valve block actuating on its own. Picture attached shows the Front Actuator Piston Regulator Valve jumping around, there is no electrical signal making this request.

So, in summary, I think I'm going to replace the CPLA block with a FPLA one, I'll pick one up off eBay.

The questions

Looking at the graph, has anyone seen this before? Does my thinking sound reasonable?

Has anyone replaced CPLA with FLPA, any issues?

The dreaded bleeding question, how do I bleed it afterwards without the special tool?

Many thanks for your thoughts

Post #722158 1st Aug 2025 8:35am
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911r44



Member Since: 30 Oct 2022
Location: Nottingham
Posts: 10

United Kingdom 


Now the graph

Post #722159 1st Aug 2025 8:36am
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Cam-Tech-Craig



Member Since: 04 Aug 2011
Location: Gloucestershire
Posts: 16380

England 2015 Range Rover SVAutobiography SDV8 Loire Blue

I’ve personally not had much experience with valve blocks at all luckily. However when my first 405 was quite young there was a TSB re changing the valve blocks. This was an end result after changing most other hardware after complaints of knocking suspension. Can you confirm whether yours was ever changed?
I presume yours is an early car?
I believe the replacement valve blocks came with multiple valves instead of just a single valve…

Hope this helps? Bow down

Post #722168 1st Aug 2025 10:33am
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911r44



Member Since: 30 Oct 2022
Location: Nottingham
Posts: 10

United Kingdom 

Hello

Yes, I am aware of the recall, I don't think mine was done. It's a 2013 car and fitted with the CPLA valve.

Thanks

Post #722174 1st Aug 2025 12:02pm
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Cam-Tech-Craig



Member Since: 04 Aug 2011
Location: Gloucestershire
Posts: 16380

England 2015 Range Rover SVAutobiography SDV8 Loire Blue

Have you asked if the TSB is still live? I guess it will be… Then they can do the job for you FOC… Thumbs Up

Post #722180 1st Aug 2025 4:26pm
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