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Well my alfa has gone all italian on me, he wouldnt start :( so called out recovery, turns out its the camshaft sensor, ive asked one of the trade guys on here for a price, so will replace it and see how it goes, strange thing tho, the guy plugged in his code reader, 2 faults showing but no codes to be found, anyway will keep you informed on the progress, once again thanks for your help thus far, i'm sure i'l need more lol
 
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an code will ONLY be stored once the engine has been started, if the engine can't start becuase of a faulty sensor that error won't get reported.
 

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hmmm why didn't the recovery man do that:confused: thanks i'l replace the sensor then plug in the code reader and see what it comes up with, thanks for the info
 

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Hmmm - not heard of a camshaft sensor failure causing a non-start.....crankshaft sensor, yes, but camshaft sensor......? Sure I've unplugged one completely and the car has started OK.
 

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Hmm ok, can you clean the sensor? or is it just replace it? ive also had the idea to just cut the cable and join both cores together and see if that solves the fault, not the right way but hey ho lol
 

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Hmm ok, can you clean the sensor? or is it just replace it? ive also had the idea to just cut the cable and join both cores together and see if that solves the fault, not the right way but hey ho lol
do job properly and dont **** about IMHO :cheese:
 

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First off, hello this is my first post here as I have not owned an Alfa since my 33 back in 1997.

I may be completely wrong as all of my experience is with off-road diesel engines but crank speed and cam speed sensors are both required by the ECM/ECU for the engine to run properly.

The crank sensor will tell the ECU when the piston is at TDC (and probably which direction the crank is turning but it doesn't know whether it is about to make an intake stroke or a power stroke without the cam sensor) The cam sensor will tell the ECU that the cam is turning and when the piston is at TDC too.

If the engine is running then quite often it will keep running without the crank sensor because it can keep track of the timing with the cam sensor but it may well de-rate itself because it cannot guarantee the timing because of the slack in the timing belt.

The engine will most probably not start without the crank sensor although not necessarily. It may start and run roughly.

If, however the ECU cannot check the timing of the cam it will assume the worst and de-rate (I.E. limp mode) it would really like to shut down to protect itself from the possibility of piston and valve colliding but highway vehicles are not allowed to do this by law for what should be obvious reasons

If it doesn't receive a signal from the cam sensor when it does get one from the crank then it will assume that the cam belt has failed so will not allow the engine to start.

Also the hall effect speed timing sensors are not something that you can clean or repair, they are not very expensive.

Please feel free to correct me if I am misinforming anyone
 

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Am i not right in believing that the ECU cannot decide to shut the engine down for safety reasons? You don't want to be in the middle of a railway crossing when a sensor fails causing the ECU to decide to shut the engine down.

I thought that was the idea of limp mode, it allows you to recover the vehicle to safety whilst de-rating the engine enough to prevent terminal damage (and so that even the most numpty driver will realise that something is wrong and maybe even get it checked out)
 

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Am i not right in believing that the ECU cannot decide to shut the engine down for safety reasons? You don't want to be in the middle of a railway crossing when a sensor fails causing the ECU to decide to shut the engine down.

I thought that was the idea of limp mode, it allows you to recover the vehicle to safety whilst de-rating the engine enough to prevent terminal damage (and so that even the most numpty driver will realise that something is wrong and maybe even get it checked out)
ecu can shut engine down :thumbs:regardless of where you are
 

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I had this issue.

At first the ECU was saying Camshaft positioning sensor or Phase sensor (depending on computer system).

We thought we found the culprit being a slightly damaged exhaust cam shorting out on the Sensor. Just replaced the cam and things went well until car failed again.

ECU read again and both Camshaft position and Crank Sensor showing as malfunctioning.

If your car is not starting the 'Crank' (RPM) Sensor has gone.

An Alfa Specialist should charge you around £100ish for the sensor and labour, it's at the back of the engine (unscrewing MAF & Throttle body will help to get to the sensor)

Once the Crank Sensor is replaced your car should start and run well, but if your injector light keeps popping up then the ECU puts the car in 'limp home mode', chucks loads of fuel into the car, your camshaft positioning sensor needs replacing, like mine still does.

Hope this helps.
 

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an code will ONLY be stored once the engine has been started, if the engine can't start becuase of a faulty sensor that error won't get reported.
That does not sound right.
My Crank & Camshaft position sensor faults were stored on the ECU and the car could not be started.
 

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Discussion Starter #16
Thanks guys for your replys, let me just tell you what is happening with the car, when it does start, after awhile the engine management light comes on, might go off again, might not, i havnt had a loss of power or performance still goes well, does this help to say for sure what is wrong??
 

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Well my alfa has gone all italian on me, he wouldnt start :( so called out recovery, turns out its the camshaft sensor, ive asked one of the trade guys on here for a price, so will replace it and see how it goes, strange thing tho, the guy plugged in his code reader, 2 faults showing but no codes to be found, anyway will keep you informed on the progress, once again thanks for your help thus far, i'm sure i'l need more lol
his code reader cant read ecu codes so get it plugged in to someone who can:thumbs:
 

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Thanks guys for your replys, let me just tell you what is happening with the car, when it does start, after awhile the engine management light comes on, might go off again, might not, i havnt had a loss of power or performance still goes well, does this help to say for sure what is wrong??
Camshaft positioning sensor needs changing if the ECU light comes on at random intervals.
It will not stop your car from turning on (that problem is due the Crankshaft (RPM) sensor is faulty and needs to be replaced.
The ECU would need to be cleared of faults before the car would successfully restart.

So to get the car running Crank sensor and ECU fault cleared, to get rid of ECU light replace Camshaft sensor and better fuel economy for starters!
 
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