Originally Posted by ymeski56

$27. Buy it:https://www.amazon.com/INNOVA-3145-F...SIN=B000EW0KHW

Not sure if the scanner is worth more than the book you get w/ it, or the book you get is worth is worth more than the scanner.

Why? Because the code definitions are broken up by, "Are you driving an OBD1 Car, or Truck?"

So regarding Code#538.
Car: Test condition: KOER (Key On Engine Running). Insufficient RPM change durring KOER dynamic responce test. ((Not enough throttle added when you were supposed to have added throttle)
Truck:Test condition: KOER, Invalid cylinder balance test due to throttle movement during test. (Throttle added out of test sequence/ At the wrong time)