172 clio will crank but not fire

[stfc87]

Basically it will start no problem and all and run as it should, but at random times it will just crank for a few seconds, but won't fire up. Keep trying and does the same everytime i turn the key, until i'm fed up! lock the car and try again and it will start? this has happened twice this week only had it 3 weeks i have read a lot about crank sensor which is bolted to the engine under the airbox, but it seems to me like an immobiliser fault as it happens at random times, has a mind of its own.

Also whenever ive been trying to start it for a while, i hear what sounds like relays clicking under the glovebox & sometimes on the driver side near the vent. I have put a new battery in the fob and put a new crank sensor in

Help!

 

[mikeh]

If it's the immobiliser, the immobiliser light will stay solid red.

If it's the crank sensor then stopping and immediately retrying starting generally works.

 

[morgam23]

I think a diagnostics check should indicate if the TDC sensor is faulty.

 

[Dan@SJM]

Crank sensors rarely show a fault. Have a look and see if the crank sensor is blue or black. Renault revised the design and changed it to blue due to this issue.

 

[stfc87]

Crank sensors rarely show a fault. Have a look and see if the crank sensor is blue or black. Renault revised the design and changed it to blue due to this issue.

hi the one i took off had a black plug and replaced it with a black plug type. I will wiggle the plug the next time it happens, though it happens randomly. I will also keep an eye on the immob light.

Thanks for the help people.

 

[not normal dan]

See if you are getting an A/C current from the crank sensor.

But strange how it starts when you lock/unlock does sound as if it could be an immobiliser issue :s

 

[stfc87]

See if you are getting an A/C current from the crank sensor.

But strange how it starts when you lock/unlock does sound as if it could be an immobiliser issue :s

Will check it with help of my dad tomorrow. Well it's done it again today and locking and unlocking didnt help.
Noticed the immobiliser was flashing fast and if i turned the key to ignition for 30 seconds and then tried cranking, nothing would happen.

 

[stfc87]

Could the UCH be the cause?

 

[jonny172clio]

Did u solve the problem????

 

[Dan@SJM]

Light flashing fast is usually a key fault.