Suspension Fault - C1A18-64

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scott schmerge

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Got a new suspension fault today. Sometimes it goes away after a restart, other times it doesn't.

IID Tool says it's C1A18-64. "Pressure increases too rapid when filling reservoir - Algorithm based failure - signal plausibility failure."

A search on this and the LR3 subforum turned up no hits. A general google search turns up some hits on a range rover forum that indicate it could be a valve issue near the air tank. The algorithm part of the code seems odd, though.

It's still under CPO, so I'll take it to the dealer early next week.
Just had it and was able to get it corrected. It’s your reservoir valve block. Easy rebuild. I need to put some new o rings in mine, but a good cleaning has kept it free of faulting.

Essentially the valve that controls air flow to the reservoir stays closed, therefore “pressure increases too rapidly”. Suspension continues to function correctly, but reservoir is also unable to fill suspension due to stuck valve. Raising to off road height takes longer than normal as well (I’m guessing).

I spent about an hour total on the repair and it cost me $0 to fix. (Least expensive fix I’ve ever had on my 8 rovers I’ve owned)

Apparently when the valve sticks the algorithm determines a blockage to the reservoir (the stuck valve) and intermittently generates the “pressure increases too rapidly” message. Another interesting symptom is when the valve sticks, the reservoir can’t release air pressure so the vehicle raises very slowly (using only compressor air instead of combination). Once the valve was cleaned, all symptoms back to normal.

For the repair:

1. Use gap iid tool (or other ECM control) to depressurize the system.
2. Remove compressor cover
3. Valve block sits right in front of compressor, remove two electrical connections and four air lines.
4. Open valve body by removing three torx screws
5. Clean four o rings in the valve body. There are three on the little metal cylinder. My fourth and smallest was stuck up in the valve body. It was very clear to me the one that was sticking as the assembly is spring activated and it was stuck together (no spring action) upon disassembly.
6. Reassemble and refit.
7. Use gap tool to repressurize system
8. Check for leaks (I heard slight leak and had to refit one of the lines)
9. Replace cover and you’re done
 

ryanjl

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Well, for me, it wasn't my block but my compressor. This is an old thread.
 

Pfunk951

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I understand that Hitachi made an updated compressor- does it operate faster than the OEM?

I'm kind of disappointed that RyanJL ruled out the tacos so early..

Mike
 

ryanjl

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Interesting...apologies on the old thread...saw it pop up and looked at content not the date. Glad you got it sorted.

Truth be told, I was a little disappointed it was the compressor. Happy it was replaced under warranty, but a little fearful that it wasn't really anything that the code would have indicated going by the charts I found online.
 

scott schmerge

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Truth be told, I was a little disappointed it was the compressor. Happy it was replaced under warranty, but a little fearful that it wasn't really anything that the code would have indicated going by the charts I found online.

Well, at least you got a new compressor out of the deal while under warranty. Valve block is an easy fix (and inexpensive).


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Ladric

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This error comes up on my 2011 LR4 "pressure increases too slowly when filling reservoir. Algorithm based failure. Signal plausible failure"
Wondering if this is also the compressor. This normally happens when I change the height but recently it was after just sitting for a few days in the cold MN temps (6 ~ 12 F). I just clear the code and it stays away for a month or so.
 

scott schmerge

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This error comes up on my 2011 LR4 "pressure increases too slowly when filling reservoir. Algorithm based failure. Signal plausible failure"
Wondering if this is also the compressor. This normally happens when I change the height but recently it was after just sitting for a few days in the cold MN temps (6 ~ 12 F). I just clear the code and it stays away for a month or so.

Yes, it’s possible that just the desiccant is shot. Not a hard job. Over time it breaks down. Otherwise you may be looking at a new compressor.

it’s also possible with corrosion in Minnesota winter that your reservoir has developed a slow leak. May be worth looking at the reservoir that sits in front of the compressor on the drivers side. My guess is though it’s desiccant (dryer beads) or compressor related


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DGAP

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Ryanjl, thanks for your posts.
I have a Range Rover Sport 2013, that has the exactly same problem ( trust me, exactly the same), and based on you problem, I have imported a new AMK compressor from Buy Auto PArts ( I live in a small city in São Paulo state, Brazil), and it's arriving today. Hope that solves the problem, anyway, just wanna to thank you for keeping posting. Best
I too have this issue. Did the compressor fix your issue? How do you see what compressor manuf. is installed. I have a 2013 L320 RRS HSE
 

ryanjl

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On a 2013 I can almost guarantee you it's an AMK. But to be certain, you can remove the plastic compressor shield and look.
 

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