Hi guys, I know this is now an absolutely ancient post, but I am in the midst of replacing the crank sensor on my 156 GTA. Having read the 147 GTA post I thought this would be a one hour job.
The hell it is! First of all I had to find the sensor, which has an accurate location from the previous descriptions for the 147. I removed the throttle body from the top to get access to the electric cables which are in the plastic housing below the throttle body. The brown cable is the crank sensor.
You need to jack the car up on the offside to get good access. There is a metal shield bolted in to protect the sensor, held in by three, 5mm allan bolts. The forward one of these bolts is a nightmare to get out as there is a stud protruding from what I think is the gearbox/diff housing. I had to unscrew the 10 mm nut off this stud before I could get access to the 5 mm allan bolt. Once the nut is off, it is still tricky to get the allan bolt out, but persevere with it.
After you have the shield out, I can see no easy way to get access to the allan bolt holding in the crank sensor. I tried and tried but could not get my hand between the exhaust pipe to get an allan key/socket in the hole, let alone attempt to remove the sensor and fit a new one!
Tomorrow i'm going to remove the front part of the exhaust manifold and bend the pipe down on the flexible pipes to get decent access. For me this is the only way to do it on the 156 GTA. My exhaust is knackered anyway so now is a good time to be looking at an upgrade. The car has done 155k+ miles so its time for a new exhaust and a bit of TLC.
If anybody has done the crank sensor on the 156 GTA, without removing part of the exhaust to get access, I salute you! Please let me know how you did it!