[mifanning]

First time on forum.  Read some posts about my problem, which some others have had.  I am an American living in France and I own a 2009 i30 1.6 CRDI 115 6MT Pack Edition (diesel) .  Yesterday, on my way to work, the warning light for "water in the diesel" went on.  Took the car to the local dealership who replaced the diesel filter and put an additive in the tank (in French: nettoyant circuit gazole) to "disperse" the water.  All seemed okay until today when the light went on again! I am not having any problems with acceleration, which was "iffy" when the problem originally occurred.  So I wonder whether the light will go on periodically until all the water is flushed out of the system?

So my question: should I go back to the dealer and say the problem is persisting, or do you think I just need to run through this tank of diesel?  Oh, I am bummed by this as I always fill my tank with the highest grade of diesel from Total.  Thanks.

[Phil №❶]

For your ultimate protection, your tank and fuel line should be drained flushed and cleaned. In Australia, it costs about AU$300 to have this done. The CRD uses extremely high pressure and micro fine tolerances in the fuel pump. Significant damage can be caused to pump, engine & injectors, by trying to flush water through with a dispersant.

[mifanning]

For your ultimate protection, your tank and fuel line should be drained flushed and cleaned. In Australia, it costs about AU$300 to have this done. The CRD uses extremely high pressure and micro fine tolerances in the fuel pump. Significant damage can be caused to pump, engine & injectors, by trying to flush water through with a dispersant.

Gee, thanks for this information.  I will call the dealer.

[Lorian]

Wasn't there also some possibility on older cars of having a defective filter housing causing the light? I think cars from Ulsan?

[Phil №❶]

There is also the possibility that member Lorian is correct too. It could be a faulty sensor.


Sadly, there is no way to be sure that your service station has water in their tanks. Try to fill only at busy stations that fill heavy vehicles. At least the Diesel will be fresh. I always use an additive in every tank to protect against Diesel bug but large amounts of water shouldn't be flushed this way.

If you  are mechanically inclined, you could do it yourself and save some Euros / Francs. There is an inspection plate under the rear seat. A syphon tube and suitable recepticle would allow total drainage. The fuel line can be emptied by manually pumping fresh fuel using the pump next to the Diesel filter in the engine bay.

[mifanning]

Wasn't there also some possibility on older cars of having a defective filter housing causing the light? I think cars from Ulsan?

Well, I did sense a lack of power when the light first went flashing so it seems the problem was genuine.  I bought the car second-hand when I arrived in France in 2011 and never had this problem before.  As for the newly installed filter, one would have to guess it's okay.  I suspect the continued presence of water in the diesel might be creating the problem.  One other thought: should I fill up the car with fresh diesel to further minimize the presence of the water?  I also will be talking with the dealer about the recommendation from the OP who suggested a total flush of the diesel.

[mifanning]

Thanks for the suggestion Phil.  I am not mechanically inclined, so I will stay away from the DYI fix but many thanks for the suggestion.

[Phil №❶]

No do not fill with Diesel. It will only make flushing more difficult. Diesel and water do  NOT mix, you can't dilute the water this way. The emptier the tank is the easier to clean.

[mifanning]

No do not fill with Diesel. It will only make flushing more difficult. Diesel and water do  NOT mix, you can't dilute the water this way. The emptier the tank is the easier to clean.

Ah, good point!