Power Steering Pressure Sensor; what is it?

It does not exist, at least not as you describe.

Although, in a more helpful vein, there's a "power steering pump pressure switch" which would fit the bill.

I would think if it failed catastrophically it would dump power steering fluid (ATF?) rather than fuel...

Mr Cheerful, I just copied what the invoice from my local garage said :-)

Apologies, "fluid" is what I was meaning to type :-( And thanks for the constructive guesswork.

So what does this do? And where is it located? Mr RAC-Man took a look from the top and said "the hose has split", so I guessed it would be somewhere high and leaked down the pipe, giving the impression the hose had split.

Many thanks for the answers so far.

Kostas

When you turn the steering wheel, the power steering pump puts hydraulic pressure into the system to make the steering easier. This makes the engine work slightly harder. An electrical switch is fitted to the high pressure part of the system. When this switch detect the high pressure, it sends a signal to the ECU. The ECU increases engine power in order to stop the engine from stalling if you are going slowly.

The location of the switch depends on the engine type fitted, and whether it has A/C.

You should not have been left stranded, although I'm not sure why you think that was nice;-). The power steering fluid would have made a mess, but the vehicle should have continued to run; the steering would be much heavier without assistance of course.

It might help you in the future to ask any Focus related questions in the news group alt.autos.ford.focus.

HTH

Chris

It did continue to run and I managed to park OK, still assisted. However something (the pump?) was making a horrible, squeaking noise, getting louder by the yard. I thought it best to stop the engine. It was on inspection of vital juices that I realised it was the PAS that was the culprit. Mr RAC man did not suggest I drive it home either, but ordered a recovery truck.

Thanks for the suggestion. I may give it a shot.

Kostas

Its vac-controlled on mine ('91 celica), just for reference.

That's interesting.

Is the vacuum part of it just for control, or does the vacuum provide the power to assist the steering? Is the vacuum generated by manifold depression, or by a vacuum pump?

Of course, many cars are now using electro-hydraulic or electric power steering also.

Chris

Its a vacuum valve fitted to the (thinks....) cant remember pump near the output, when the main PS pump valve moves and "aids" steering the pressure also shifts the small valve, this provides a vacuum "leak" which raises idle by a fixed amount.