I have a 2001 S40 75,000 miles, and it won't start intermittantly. When the key is turned in the full start position
the fuel pump turns on and all other electrical stuff is working, but the engine won't turn over.
We took it to a Volvo dealer and after $$$ they couldn't find the problem.
I have seen on one forum that someone had to have their ignition cylinder lock replaced for a similar problem.

This problem seems to happen on cold days and after the car has run for a while. It used to only happen once in
a while, now it happens almost every day.

Tech, or anyone else, what do you think? I am tired of getting stranded....

Thanks for your help,

Hoopicide

 

i'm having the same problem on my 2001 s40, 53k miles. my mechanic told me that volvo told him could be air sensor,thermostat sensor or cooling sensor. does this make sense to anyone? i don't want to change all these sensors unnecessarily.

 

This is odd stuff. I hope i dont have this issue. GL!

 

Yup, that makes sense.

BB
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what makes sense? which sensor should i change, or should i change them all at the same time?

 

Could also be a bad Flywheel sensor.

 

They're all possible sources of the intermittent starting fault that you are experiencing, assuming that coils/leads & plugs are all OK, so the reply I gave on 31/12 answered the question you actually asked.

Your profile doesn't say which year & model of S40 you have & which country you are in. This is all relevant info. that could help with fault finding. For instance, for certain countries, non-turbo models were fitted with an inlet air pre-heating system operated by a wax thermostat type arrangement in the air cleaner housing. If that were faulty then this could lead to starting problems in certain circumstances but not in others.

As ever Tech is spot on, the flywheel sensor could be dirty, loose or breaking down.

If you have or can get a good workshop manual, this will advise you on how to check most of the items/sensors mentioned individually, rather than paying out to replace all of them one-by-one until you hit paydirt. You mention your mechanic - he should know which bits can be tested & how.

BB
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its a 2001 s40 1.9 turbo. bought & driven in ny. 53k miles.