Aye corrosion is never good on any cars electrical cables and from what i have read esp on the fiat it really needs cables and battery to be in top condition,so it's always a wise place to start,others with more experiance will be able to tell you better but i would also clean the boby work also where the earth straps are connected,hope you get to the bottom of it soon

Originally Posted by brocherboy

Alot of people (included me) are/was having trouble with their car having "intermittent" errors and "loose connection" with help from forumers found this to be caused by a faulty crankcase sensor
One main tell tail sign was car starting and then when stopped would not re-start for 15mins or so
So this is a very quick job to do and cheep
The only tools required are 0.5 torque bit and ratchet,torch,white tie strap or something simular
Firstly disconnect battery earth and locate the brown connector behind the ecu's looking in from the passengers side (arrowed)


Then unclipped the car tie strap by simply pushing together (TIP attach the white tie strap loosly and let it slide down the sensor cable ) this make the sensor easyier to trace when under the car
Jack up the car from the drivers side as this makes it easier to reach the sensor PLEASE REMEMBER SAFETY USING AN AXEL STAND AND CHOCKING A BACK WHEEL ,(i did,nt remove the undertray as it was not nessasary as you are looking directly above back of the sump)
Once under your car you will be able to trace the cable to the sensor as it is hard to spot being directly under the starter motor ,using the torque bit remove the only screw and pinch together the remaining 2 car ties to release the cable





As you can see with the sensor above arrowed the tip is totally gone and deeply scored making it hard for anything to get a reading from it
Once free i went into the engine bay disconnected the brown connector then pulled it up taking note of its path to replace with new one

Picture of new sensor as you can see with 1mm tip


Now simply feed through new sensor ,and fit ,it will feel slightly slack when you insert only because their is no friction with oil ,replace screw and secure cable into car cable ties
Before i reconnected battery i checked over starter motor wireing and sprayed with contact spray might as well as i was under there
Sorry if it seems long winded first guide i have done ,the sensor took me 20mins and only cost £31 inc postage shop4parts and has sorted me out so hopfully you to

The standard screw head on the Crankshaft sensor bolt is a T-30, replacement is a 40, Great guide though, just threw me off the the 0.5. Easy Change, and Great Guide

Am really glad this guide is still helping
And thanks for the input on torque size