Just wanted to know if there is anything i can do to help/find out what the problem is with this issue. Iv seen a few people have this problem. Its been warm enough, not had the climate control on much and do a 40 miles round trip to work on the motorway very day. Had the car for going on two weeks now and apart form a couple of speakers rattling its the only problem iv come across. its a 2011 focus 1.6 tdci.

any advice welcome thank you   

When the control light of the Start/Stop button is not lighting up or flashing combined with a warning message the Start/Stop system will be fully functional. In most cases a non functional Start/Stop system is caused by a bad battery which does no longer have its full capacity Even a small loss of capacity can be the reason of the non functional Start/Stop system.

When I bought my car it was only 1 Year old. My car is originally a 1 owner German car that was only used for 6 Months. After these 6 months the car was stored for another 6 Months (because of tax reasons) before it was imported to the Netherlands. When I test drove the car the battery cover was lying in the boot which suggests that the battery has been flat and the battery has been charged or the car has been jump started. As a result of this the battery did not have its full capacity and the Start/Stop system was not functional. After I charged the battery the system worked for 1 or 2 times and then it stopped working. There were no stored DTC codes that related to the Start/Stop system so the system should have been fully functional. After a few Months I replaced the battery and since then the Start/Stop system is fully functioning.   

9 hours ago, AndyHill24 said:

its a 2011 focus 1.6 tdci

Is it Mk2A or Mk3? (Close to the changeover time).

However I do not think Mk2A ever had stop-start, so it is probably Mk3.

Mk3 has an "intelligent" battery monitoring system that will try to detect state of charge in the battery, and will not Stop (as in Stop-Start) if it thinks there is a problem.

In this case testing the battery will need a sophisticated battery test unit that is valid for your type of battery. May need a visit to a garage!

Mk2A is a bit simpler, and basic voltage measurements at the battery terminals (engine running, then engine stopped with headlights on) should give an adequate guide to battery state.

As Wilco says, battery has to be 1st suspect, then it gets harder, unfortunately.

Peter.

Ye its a Mk3. No problem, will just have to work out if the cost of a new battery will save me that much money with the stop start.

 

Thanks 

I doubt it, batteries for them are fairly expensive.

54 minutes ago, AndyHill24 said:

new battery will save me that much money with the stop start.

The environmental benefits of stop-start instantly vanish if batteries need more frequent replacement. Like so many of the bureaucratic "eco" schemes that governments & big corporations love, when you look at it overall, it is usually of negative benefit.

Stop-Start only stops if the battery is near perfect, if the aircon is not on, the engine is fully up to temp, but the rad. fans are off, wipers not on full, the heated windows are off, etc. etc. So in the real world, that is probably not often. There are also discussions about stopping the engine if the turbo is still red hot, like traffic lights on a M/way slip road. And diesels use very little fuel while idling, and if their Euro 5/6/7 emissions kit is up to scratch, not much nasty stuff.

Mining lead, and recycling lead acid batteries must be much more environmentally damaging! (And lithium or nickel are unlikely to be any better.)

So I would not worry about it, keep using the battery until it looks like giving real problems.