Peugeot 508 Allure Year 2012 2.0 HDI Master Clutch Cylinder

[exus28]

Hi lads,

I’m reaching out because I’m genuinely starting to believe my 508 Allure (2.0 HDi with the electric automatic handbrake) was built in a parallel universe. I’ve spent the entire day hunting, and it is absolutely impossible to find a replacement clutch master cylinder anywhere on this planet—aftermarket or genuine.

The physical part on my car has the factory stamp 9678117180, but if you type that into Google, Euro Car Parts, Autodoc, or eBay, you get absolutely zero results. It’s like the part doesn't exist. Even the updated official part number given by Peugeot (9689017580) draws a complete blank online. The only thing that pops up is a single mental Euro Car Parts listing for an absolute joke of a price (£519!), which is a complete non-starter.

I’ve seen a few cheap ones over in the EU, but they are all for Left-Hand Drive (LHD) models. Even if they weren't sold out, swapping them over or trying to modify them is a no-go. If you twist the rod or flip the position, the internal magnet on the cylinder won't line up with the external Hall-effect sensor track, meaning the car's computer won't register the pedal is down and the engine won't even crank.

Has anyone else ever dealt with this nightmare from another dimension? I feel like I'm losing my mind here. If anyone has a secret supplier, a cross-reference number that actually works, or knows a workaround that doesn't involve spending £500 on a plastic cylinder, please let me know.

Cheers!

[PaulC5]

Have you tried a Peugeot dealer, a search came up with this which suggests it should be about £162 https://peugeotcitroendsparts.com/produ ... 17180.html

Another site suggests full price is £210, if they had one it would be £178 but you could contact them to check https://citroendirectparts.co.uk/produc ... -cylinder/

Is your photo the actual master cylinder from your car as a google lens image search against it comes back with this, a DS3 master cylinder at £300 https://citroendirectparts.co.uk/produc ... -cylinder/ and part number 9676535980.

[exus28]

Thanks for the links, Paul—you are really getting to the bottom of this.
To answer your question: yes, that photo in my original post is the actual old master cylinder out of my car.
You are 100% right about that last link for the DS3/2008 part (9676535980 at £303.34). Looking at it, it is 1 to 1 identical to the physical unit I just pulled out of my footwell. The pipe connections, the pushrod, and that exact external molded tracking rail for the magnetic sensor are a perfect match.
But here is my dilemma: my old electronic sensor works completely fine. I don't want to buy a £300 kit just to get a sensor I don't even need, especially when the first two links you found prove the "bare" standard cylinders are only around £160-£170.
More importantly, if I did risk buying that identical-looking £303.34 which is OUT OF STOCK, DS3 unit, will the 508 ECU actually work with it? Since it's programmed for a different chassis, I’m worried the internal piston travel or magnetic threshold will be slightly different or sensor chip, causing the 508 computer to flag an error and block the engine from cranking anyway.
Has anyone actually cross-fitted this exact sensor-rail cylinder style between models? Or is there a way to get just this specific casing without the bundled sensor markup?

Cheers!

[PaulC5]

A search shows 3 Peugeot dealers in the Manchester area, I would visit one of their parts departments and see what they say if you have not already done this.

[exus28]

Hi everyone, just a quick update on my ongoing clutch master cylinder issues.
This weekend, I managed to source a used master cylinder from a 1.6 HDi Peugeot 508 SW. Visually, the unit is identical to my 2.0 HDi version; however, upon closer inspection, there is a clear difference in the internal piston. The 1.6L piston is longer, and the pedal travel feels noticeably shorter.
While the car starts, the clutch operates, and the gears shift, it appears the slave cylinder is only getting about 80–85% travel. Consequently, I am now getting fault codes P0805 and P0808, which are exactly what I feared. As a result, my cruise control is now disabled.
I am planning to try one last desperate attempt: swapping the sensor from my original unit onto this 1.6L cylinder, just in case the ECU accepts the signal. That said, I suspect this has a 90% chance of failure, as these systems are precisely calibrated at the factory and the ECU is likely expecting a very specific signal range.
I have already checked both Diagbox 9.85 and Thinkdiag+ for any gearbox learning or clutch adaptation procedures, but I haven't found any relevant options. It seems this car is extremely picky, and the part likely needs to be an exact match for the engine, specification, and trim (such as the electronic handbrake). It’s becoming clear why this part is so difficult to source online.
Has anyone else dealt with these specific codes after a master cylinder swap, or knows of a hidden way to force a re-learn in Diagbox? Any advice would be greatly appreciated.