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C4 AL4 high oil pressure after EV replacement	Please Register to enjoy additional Member Benefits

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majndfak United Kingdom

Wed Jun 10 2020, 12:37pm

Member No: #54752

Joined: Oct 02 2019
Location: Aberdeen

Hi guys, let me start from assuring you that I did search forum for an answer, however, couldn't find my problem anywhere.

So a couple of months ago I started getting service along with gearbox faulty message and rough gear shifts. Upon scanning with Diagbox it turned out to be P0006: pressure regulation variation/recommendation fault, this and other forums suggested notorious electrovalves problem. Replaced them a week ago, dismantled and cleaned the valve block (didn't touch any of the sequential valves though), and if anything it made things worse and rendered car completely undrivable. When changing gears parked there is distinct noise along with noticeable jerk when putting drive gear. When I tried to go for a test drive within a couple of seconds there was a loud thud and box went into limp mode.

I monitored variables through Diagbox and this is what I found (see graphs below):
- Oil pressure starts from 11.2 bars and the gradually falls as the oil heats up
- Pressure almost doesn't change when putting into different gears
- Whenever there is any load on engine pressure instantly goes to 11.2bars regardless of a gear

Because of this as soon as I try to drive gearbox goes straight into limp mode with error P1167 Pressure regulation fault (difference / reference value)

I ruled out the possibility of broke oil pressure sensor since I can see that voltage follows the pressure and from what I've read in case of a defected one pressure is constant.

I repeated the oil levelling procedure to make sure it's not the fault of me overfilling the oil, sadly no change. On a side note, I put 4 litters of a new ATF LT71141 oil and got 5 litres out, is it normal?
Another thing is that I noticed that on old fault reads main pressure regulation valve status says activated whereas now is deactivated. Does it mean that electrovalve is broken?

Both old and new EVs were of the Borg Warner type and oil wear counter was correctly adjusted. It's 2006 C4 mk I 1.6.
I will highly appreciate any suggestions from you. I'm helpless at the moment, no idea what I can do more to fix it.

I attach more graphs that capture oil pressure over time as the oil temperature increases.
Cold engine:

Warming up about 35C:

Reaching operational temperature:

Warmed up:


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