CK engine light after moderate acceleration

[hotdog789]

2003 PT Cruiser GT (turbo): The engine runs great but the check engine light comes on about a minute after I accelerate from 40-70 mph or from 50-75 mph, either going on an on-ramp or while passing. Lots of acceleration, but then the light comes on about a minute later (maybe less). I can clear the light by disconnecting the negative battery terminal, but the next time I punch the throttle on the highway, the light comes on again. The engine temp gauge usually reads just below 50%. Any ideas?

[hotdog789]

Just got back from Advance Discount Auto. The error code is P0551 "Power Steering Pressure Sensor". Any ideas why?

[CREWZIN]

Can't tell you why, actually it sounds odd, but if you decide to swap it out this might help.

[quicksilverdon]

Check the Power Steering fluid level.
It takes ATF + 4.

[hotdog789]

Thanks to both of you for your responses. When I bought the vehicle, the power steering fluid was low, so I topped it off with Prestone power steering fluid with stop leak. I'll try draining that out and replacing with ATF +4 before replacing the pressure sensor switch.