Hi

I changed my timing belt, started up the engine and everything went ok.
Turned off engine, 5 min later I was out for a test. But engine won't start.

Checked errorcodes,

Fault code N1
RPM sensor, No signal
Error intermittent
Engine speed: 50rpm


So, I changed this sensor, (the one that reads the cranckshaft)
but still no start and same errorcode.


Anyone with a clue what I could be?

Check if there isn’t a break in the sensor wiring...

So, a new sensor i mounted, checked it and it was ~520 ohm.
Pulled the contact in the ecu, measured it and it was no wire break (made a loop in the connector so I could measure it)
When i connected my multimeter and measured it when trying to start, I get signal, so sensor is working.
I'm using AlfaOBD and checking rpm sensor when I'm trying to start, and get's 62 rpm, but also an error code that rpm sensor, no signal. Error intermitent.

Anyone here have a clue what could be wrong?

Can't recall if the "B" has a camshaft phase/timing sensor?

On Fiat's that have this then it is not uncommon when using make shift sprocket locks to accidentally damage the camshaft(s) sensor.

Other possibility is that you have accidentally widened the gap between the crankshaft and the sensor. The sensor needs to be quite close to the timing pips. Workshop manual will tell you what that distance should be.