[CREWZIN]

From PT Do-It-Yourself.net

I have a 2001 PT with 59.6k miles. Recently, while going to fill up with gas the engine (MIL) light on dash came on. I ran the self-tests and got this DTC - P0551, Power Steering Switch. Is this something I can fix or change out, or is it a dealer repair. I have always worked on my own cars, and rebuilt many engines in the old days. Thanks in advance. - Roger, from South Carolina.

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A DIY'er with automotive experience could probably replace the switch, if it were diagnosed as being faulty. However, as you are probably aware, DTC's are the result of a system or circuit failure, but do not always directly identify the failed component or components. Personally, I would have a diagnostic run before replacing the switch.

P0551 (M) - Power Steering Switch Failure: Incorrect input state detected for the power steering switch circuit. PL: High pressure seen at high speed.

Power steering pressure switch - A power steering pressure switch is used to improve the vehicle's idle quality. The pressure switch improves vehicle idle quality by causing a readjustment of the engine idle speed as necessary when increased fluid pressure is sensed in the power steering system.

The pressure switch functions by signaling the powertrain control module that an increase in pressure of the power steering system is putting additional load on the engine. This type of condition exists when the front tires of the vehicle are turned while the vehicle is stationary and the engine is at idle speed. When the powertrain control module receives the signal from the power steering pressure switch, it directs the engine to increase its idle speed.

This increase in engine idle speed compensates for the additional load, thus maintaining the required engine idle speed and idle quality. The power steering pressure switch is mounted directly on the backside of the power steering gear. The replacement procedure is available through the Pit area on the site.