Phase sensor 8v model

Calling on the collective knowledge of this group again… ( bike is a 2012 1200 Sport 8v)
So following a successful change of faulty oil pressure switch, I found I had an oil leak. Ran the bike for about 15kms to check the pressure switch and found the left side of the engine dripping in oil. Traced it to the Rotational Phase Sensor where I could see it bubbling out on tick over. Ordered a new gasket but on fitting found there was also an ‘o’ ring around the top of the sensor body. So replaced that also from my stock (the replacement was a slightly fatter one). Put it all back together and now find that the motor won’t run on tick over; it’s OK with the throttle open, but stalls at tick
So, is there something critical in the installation of this sensor (it’s purpose is something I don’t understand) or do I have yet another issue to deal with?

BTW, I live in France so taking it to one of the clubs favourite specialists is not an option right now.

If it’s anything like the older phase sensor there will be shims under it to correct the air gap between it and the phonic wheel, sounds like the air gap is too big or the sensor is defective

Thanks Phil, confirms my fears. The spare ‘o’ ring being much fatter than the original is what’s giving grief I think. Put the old one back and the motor runs much better (but the leak is back).
Rgds, Rich

New sensor ,old shims should sort it

In the manual I am pretty sure that it states the air gap between the phase sensor and the gear wheel that it takes its timings from. so by putting a larger O ring on it makes the gap bigger and the magnetic field is weaker [someone correct me if I am wrong]

Could possibly try ACC Silcoset sealant, with the old ‘O’-ring. Wonderful stuff but not too cheap tho.


I would guess all surfaces had to be thoroughly degreased on application.

Replaced the one on my 09 Stelvio a while back, no O-Ring, just the Shims, no leaking.
A smear of any good quality proprietary Sealant will do, Hylomar, Hermetite, etc.

Just to wrap this one up, I sourced a OEM ‘o’ ring, fitted and seems to have cured the leak. Still needs a decent road run to be sure - just waiting for a nice day, thank all…

Good to hear.

Meant to mention previously, the Sensor is a common part on many vehicles, like the Oil Pressure Switch, can get them from any good car spares shop.

My Breva 1100 started dying at tick over and that turned out to be a dead sensor

Replaced with a generic one and normal service was resumed

Checking the air gap was a bit tricky but if you replace all the shims that came off it you should be OK.

As long as they’re both the same size, from the Flange to the ‘Tip’, then yes.
Easy enough to compare new with old, and Shim to suit if necessary.