Error codes 13 and 52

[bhawkins]

Should my car start the cooling fan while idle (90 all-trac 3s-gte)? the car is idle for about 5 minutes and then the engine check light turns on, that's about the time that a casual car needs to start the cooling fan, so i'm suspicious of my thermal switch. i ran diagnostics and my check engine error codes flashed 13 and 52
these codes are
13 RPM Signal No NE signal to ECU when engine speed is above 1000 rpm
52 Knock Sensor Signal Open or short in knock sensor signal

WTF?!? there is no cooling fault, and oh, what the hell is a knock sensor?

[toyomoho]

The knock sensor is screwed into the block. It job is to pick up vibration. It tells the ECU if the engine is knocking, that ping you hear, pre-ignition. The ECU then retards timing. Check sensor or wiring. For the other code, check the distributor circuits, the ECU is not reading RPM.

Problem could be as you state, the car is overheating. Check coolant temp, the fan should kick in at about 199F. You may not get a code for coolant overheating, can say for sure.