My check engine light code is P0551 - faulty power steering pressure switch. I found a power steering pressure line hose at O'Reilly's/Checkers. Do you know if the switch is part of this because they don't offer just the switch.

Here is the description for the code. You need to check the sensor and the wiring back to the computer.

P0551 DODGE Description Power steering pressure (PSP) sensor is installed to the power steering high-pressure tube and detects a power steering load. This sensor is a potentiometer which transforms the power steering load into output voltage, and emits the voltage signal to the Powertrain Control Module (PCM). The PCM controls the electric throttle control actuator and adjusts the throttle valve opening angle to increase the engine speed and adjusts the idle speed for the increased load.
Read more: http://engine-codes.com/p0551_dodge.html#ixzz21xtT1DTz

P0551 is for the power steering pressure switch. This is a switch that is threaded into the back of the steering rack. It's job is to tell the engine controller when pressure increases in the system from turning the wheel at low speeds, and the engine controller can increase the idle speed slightly to compensate. It's not incommon for these switches to fail.

You'll have to get at it from underneath the car. Look on the back of the steering rack and find the only electrical part on it, that's the switch you are after. Unplug it and check for signs of fluid leakage into the connector. Very often when they fail they will leak into the connector. This code setting is almost always the switch, but if you find fluid in the connector it's bad for sure.

This switch probably is a dealer item, but there should still be plenty of them around. Did you give Auto Zone a try? Or visit Rockauto.com, with this sample IMAGE LINK...

Hope helps.

Error code P0551 which reads in the Chrysler PT Cruiser computer codes as "The power steering switch may not be working".For this error the switch has to be replaced.
The power steering pressure switch is on the steering rack. It senses the pressure in the system, and when the pressure goes high from turning the steering wheel, if you are at idle it will raise the idle speed slightly. you may not even notice that it's not doing it anymore. This isn't an uncommon problem on these cars. It's very likely that you'll need a new switch. It threads into the back of the steering rack and has a two wire electrical connector. ------------- This will help.Thanks.Helpmech.

i would check the power steering fluid to make sure it isn't low. if that checks out then i would just keep an eye on it.

code po551 is power steering pressure switch circuit failure.

you need the power steering performance switch. around $30 at autozone. I am not 100% sure of the name. Basically what it does is raise the idle when turning at slow speeds to keep the engine from dying on you.

It's a $10-$15 switch threaded into a power steering pressure hose just below the power steering fluid reservoir on the driver's side of the engine near the front. Look at the reservoir cap, slightly to the right (facing the front of the engine), and down a few inches. Unplug the 2 wire connector, then hold the boss the switch is screwed into with one wrench and turn the switch with another wrench. When it comes loose, plug the opening with a finger so you don't drain all the fluid and quickly screw in the new switch. 5 minute fix, then have someone clear your trouble codes.

CODE PO551 -POWER STEERING PRESSURE SWITCH CIRCUIT FAILURE. CODE P1684 - BATTERY HAS BEEN DISCONNECTED.

P0551 Power Steering Pressure Sensor Circuit Range/Performance
There is a switch that senses the pressure of the hydraulic fluid which reflects how hard it is working (e.g. like when turning at low speed or when stopped). It then opens the switch (which is normally grounded) and a wire to the powertrain controller senses that and increase the idle speed accordingly so the engine doesn' falter. Here is an exchange I had earlier with another owner about it.
"The switch is located on the back side of the power steering gear. It is supposed to raise the idle speed when you are turning the wheels at low speeds when the system will require more pressure and thus otherwise drag down the idle. The wire to the switch is dark blue/light green (signal) and a black ground; and the signal wire goes to pin 45 of the powertrain control module. So you might check the connector at the switch and the connection to pin 45 of the controller, from pin 2 of the plug...
All I can add is that if you locate the two high pressure lines that run to the steering gear from the power steering pump you will find the switch right next to where those two lines connect to the gear. It no doubt just screws out and then install the new one. The manual says that you remove the electrical plug, lifting the locking tab carefully. Then it says to use a crowfoot wrench and extension to remove the old one. The steering fluid will run out so be prepared to clean catch it, and be ready to screw in the new one to minimize loss. If you catch the fluid in a clean pan you car reuse it. The torque spec with a crowfoot wrench is 12 foot pounds and you have to be careful not to exceed the limit or you may ruin the fine hydraulic threads on the steering gear and then you have a potentially expensive problem. So if you can't get a crowfoot that fits the sensor (when you buy the replacement you can see what the size it) and don't have an extension and a torque wrench you may want to let the shop do it. Make sure the electrical plug is in place with the locking tab engaging the tab on the switch. Refill the power steering reservoir. Start the engine and then turn the steering wheel from lock to lock several times to bleed the air from the system. Use only Chrysler power steering fluid if you loose some of it."
I doubt it has anything to do with the fluid, unless the code started right after that. If the wire seems OK, then the question is the switch stuck open (measure that) or is the pressure really too high when you are driving at normal speed or not even turning the wheel. That would have to measured with a gauge. Let me know what you learn, please, or have further questions. Hope this helps I know alot of info but should help you please rate thank you

Hello. I assume you have a 4.7 liter engine. Here is a picture of its location: