Change the crankshaft position sensor on Citroën C5 1.6 hdi

Raise the car and place a jack stand under the right side member or under the subframe

remove the wheel using a 17mm wrench

The studs will have been previously released unless you are using an impact wrench as is the case here.

remove the wheel arch cover (there are 2 clips and 2 screws, T30 torx key)

There should also be 1 or 2 screws from the protective casing under the engine to remove but this is missing on this C5.

disconnect the sensor

unscrew the sensor fixing screw using a 10mm wrench

unscrew the lower timing cover screw using a 7mm flat wrench

This will save us from having to disarm the accessory belt tensioner roller and remove the damper pulley.

On this C5, this crankcase screw was stuck so I still had to undo the pulley. We can see in the next step that the damper pulley is no longer in place, I replaced it and tightened it to the torque and angle afterwards. But it is normally not necessary to touch the pulley or the belt.

pry the timing cover aside using a flat screwdriver

rotate the sensor

and remove it

compare sensors

clean the area where the sensor is housed on the engine block (I used brake cleaner)

Use the flat screwdriver to spread the lower casing and insert the sensor by rotating it

tighten the sensor retaining screw (10mm wrench) and the lower timing cover screw (7mm open-end wrench)

and reconnect the sensor plug

turn on the ignition, connect the diagnostic tool and read the fault

then delete it

start and check that everything works

The car starts and the engine light has disappeared, the sensor was indeed the cause.

reassemble the wheel arch cover

I noted that the discs/pads were completely HS, I replaced everything immediately.

reassemble the wheel and tighten the studs quite firmly by hand

remove the candle and the jack and finish tightening the studs, torque of 100N.m