I Have an M-Reg WRX Import (1994) and it sometimes will not start for 10 to 30 minutes when warm. Always starts from cold and nearly always from hot!

The Engine light diagnostics show that the camshaft position sensor has had problems so I've ordered a new one...I can't see how this would produce a temperature related issue though, does this make sense or is it more likely something else??

P.S. The car always jump starts!

 

What are the symptoms? Does it turn over? Fire? etc.

 

mine is doing this aswell, been told that the sensor works off a magnet and when it gets hot the magnet gets weeaker.
How much did you pay for your new 1?

 

This is true, the cam and crank sensors contain a magnet in a coil and generate a small voltage as the cam and crank rotate.

If you connect a multi-meter to the sensor and pass a screw driver accross it you'll see a low voltage generated.

 

classic signs of a failing crank sensor.. cleaning it might help for a while.

 

One way to tell which sensor is failing (cam/crank) is to get some freezer spray (used for electronics testing or freezing pipes) and give either the cam or crank sensor a squirt when it's failing to start. When you hit the right one it will start no problem and you'll know what to replace.

JGM - What exactly is cleaning the sensor meant to do? Mine were clean after 100k+ miles and they are sealed units anyway.

Matthew

 

they are a magnetic coil and they slowly become less sensitive and removing the layer of dirt from them often resolves the problem unit the dirt builds up again..

Mine at 100k were covered.. having just pulled the engine and moved them to the new engine at 186k they were clean.. nothing more than a couple of spots of dirt..

Simon

 

Thanks for that - I'd seen the advice to clean them before, and after replacing mine couldn't work out why.

Matthew