Intermitant Starting Issue

[Gavin J]

I've got a phase 1 172 that has got a really annoying problem...

Basically about once say every 4 weeks or so it simply won't start, turns over but will not fire.

At first i thought it was an immobiliser issue as it would be fine if i left it for a bit and tried it again, but today it did it again and i disconnected the battery - assuming this would reset the immobiliser if it was alarm related - but it still didn't start

So left it for 10 minutes and its started again....

This happened to me when i borke down in germany and the german recovery guy, turned the ignition on and off 3 times got out the car set the alarm got back in the car and then it started......he could speak no english but just pointed at the alarm sticker...factory fitted alarm by the way.....

Any ideas? could this be a dodgy crank sensor or is it likely to be alarm related?

 

[Sean6545]

Crank sensor is the probable cause. Tighten the pins on the connector or get a new one fitted with the new piece of loom.

 

[MarcC]

My mate's 172 did this, but he never got to the bottom of it before it was sold.

 

[Derelict-UK]

trying not to state the obvious but have you checked the battery?

 

[Terry172]

Does your mpg etc reset everytime? If so I would say change the battery and it will be fine

 

[geesus69]

my hybrid mashup does this every now and again

i'm 99% sure i have traced it to a dodgy ign live to the ecu at the connector plug, worth having a poke around with a multimeter for peace of mind for sure