Replacing the water pump will not cause the check engine light to come on. Either it is a coincidence or you have accidentally disconnected a wire or damaged a sensor somehow.
Check engine light will come on for various reasons. The o2 sensors could be one of them. If your belt breaks the light will come on and the engine will over heat. I mentioned the o2 sensor because when it comes on for this reason some people have had that light on for years without replacing the sensor.
Most likely the wiring to the abs sensor on one of the wheels has been damaged or become unplugged. Check all wiring in the area of the struts.
unhook both battery cables for a few minutes
Unfortunately there is no fixing an O2 sensor. If the "check engine" light is on due to an O2 sensor, it can only be remedied by replacing the bad sensor.
The sensor is damaged or missadjusted.
You may have damaged an ABS sensor or ABS sensor wiring. Go back and check each wheel.
Check to see if the wiring is damaged.
Yes - as the sensor could get damaged in the collision.
If an engine light is still on after replacing a fan's radiator sensor in a RFW engine the coolant sensor should also be checked. If the coolant sensor is bad it will send an error code to the car's computer.
The check engine light for the 2001 Isuzu Rodeo often comes on because of a sensor that is damaged or malfunctioning. The most common sensor is an oxygen sensor and when reset, this often allows the light to be reset.
You may have mis-aligned the sensor when you replaced it.