A few weeks back my 57 plate petrol Vrs developed a hesitation around 2k to 3k rpm. No faults were logged and after checking the basics still no cure. I then started checking the vacuum pipes and found one with a split. I glued the split and it didn't cure it. I ordered the part anyway 1KO612041GM (BM was originally fitted but is no longer available) plus a blank 056129777. On closer inspection and checking the one way valve in the assembly it appeared the valve was at fault. Now I've fitted the part, the hesitation has gone and it goes as it should do.

Incidentally the mileage is 81K.

Thanks for reading....

Good of you to put the fix up,will help other members if they get the same problem.

A few weeks back my 57 plate petrol Vrs developed a hesitation around 2k to 3k rpm. No faults were logged and after checking the basics still no cure. I then started checking the vacuum pipes and found one with a split. I glued the split and it didn't cure it. I ordered the part anyway 1KO612041GM (BM was originally fitted but is no longer available) plus a blank 056129777. On closer inspection and checking the one way valve in the assembly it appeared the valve was at fault. Now I've fitted the part, the hesitation has gone and it goes as it should do.

Incidentally the mileage is 81K.

Thanks for reading....

What part is it you replaced as part numbers are over my head, I have the same problem as you so this would be very helpful

I believe he may be refering to the brake servo hose which includes a none return valve.