Help! Over Heating And Check Engine Light

[ag400]

Ok. I have a SC400 (92' 185K) and a week ago the car started over heating (pin went to the 3rd tick mark on the temperature gauge) while I was in traffic (I turned on the heater to reduce the engine temperature). Also, the check engine light went on. I took the car to the mechanics the next day and they changed the thermostat and cam sensor. The next day, I drove the car from northern CA to Southern CA with no problems. Six days later, my car started over heating again and the pin went to the 3rd tick mark on the temperature gauge. After the car's temperature reached the 3rd tick mark, the check engine light went on again. I have a code reader by INNOVA. The code reader makes the check engine light blink and you can figure out what the problem is.

Question One: Is this the only way you can figure out what the check engine light is for?

Question(s) Two: The code reader specified that the check engine light was giving out a code 13. The manual describes this code as an "engine speed (RPM) sensor above 1000 RPM." Possible cause, "Distributor or circuit, ignitor or circuit, starter or circuit, ECU (non-turbo models)." What does this mean? Can this cause the car to over heat? What should I do next? Buy a service manual and figure out the exact problem or take it to a mechanic?

Other than the temperature problem, the car seems to run fine.

Question Three: Is it normal for the temperature to go up to the 3rd tick mark on the temperature gauge? I've had the car for a few months and the temperature has always been at the 2nd tick mark.

Question(s) Five: The two times I've noticed the temperature rising, I've always started the heater. This really helps reduce the engine temperature but I wonder if this is necessary? Shouldn't there be an electrical fan that reduces the temperature automatically? If so, when does this turn on?

Question Five: Can the over heating (up to the 3rd tick mark) have caused the check engine light to turn on? What other problems can happen at this temperature?

Question Six: What should I do about the over heating (If what I'm experiencing is considered over heating)? I've changed the thermostat but I haven't changed the water pump or cleaned out the radiator. Also when I first got the car I took it to the mechanics and they changed the timing belt and spark plugs, did a transmission flush, and a break fluid flush

Question Seven: Is this something I have to fix immediately? I'd like to drive the car for a couple days until I decide where to take it. (While I drive the car, I'll make sure to keep an eye on the temperature).

Question Eight: Does anyone know a good place to take the car? I live in LA.

Thanks for the help,

ag400