How do you reset the low oil pressure warning on a xsara Picasso?

It's not a reset you need! you need to solve the problem.

The warning signal and audible bleep are telling you to sort the problem out.

If you check your oil level and it is OK, you may left be wondering what is causing the problem?

Though LOW OIL PRESSURE isn't always about how much oil you have in the car, the problem is how the oil is being distributed around the engine.

My advice is have a look at the oil. Is it black? Runny? Like thin treacle? If so, dump it and put the same grade of oil back in the vechicle. Check the filter! It's located at the front of the engine (pretty central), On a Picasso it's close to the radiator, so you'll need a 27mm socket and a long extention to release the cap.

If the filter is clogged then it will need to be changed.

Of course there are other things that cause the problem, oil pump or oil pressure switch maybe faulty, though changing the oil and filter is simple and can save you an expensive repair.

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I had a problem where the low oil pressure warning was displayed on the dash. I found that if I switched the passenger airbag off, then on again the message disappeared. It worked for me (no idea why). It is worth a try as its very easy to do.