Pull the plugs and turn the engine over to force any water out. Change the oil. Probably change ALL the fluids (trans, diff, brake). I would disconnect all the electrical connectors one at a time and put in dielectric grease to stop any corrosion issues. Also WD 40 just about anywhere else I thought would need to get dried out.
Assuming you bout it right out of the lake, pull the plugs, drain all the fluids, let it sit in the sun to dry. Replace the fluids, Then crank the starter for a wile (with the plugs out... unplug the coil pack first) This will blow the water out of the cylinders. Then do a compression test if you care to. Put the plugs back in and you may be fine.
Most connectors are gold plated and shouldn't get too crusty but just check for the connectors.
One last suggestion is if you have to change the computer with a new one and then you need to code with the car.
If you are going second hand which i did, you need the ecu, module, key and dash as they are all interlinked.
OF COURSE YOU MUST CHANGE ALL FLUIDS AND I MEAN ALL.
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