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My car, sometimes, refuses to start.

871 Views 13 Replies 6 Participants Last post by  The Dog
I have a 1999 AEB 1.8t passat.
In the last 4 days I have a weird problem.
If I try to start the car, after 1 hour or least that the car run, the car would not start. It will eventually start after 15 or more attempts but the car will smell petrol. This think happens rarely and I can not “make it happen” so I can show to my mechanic the problem……
I think that the problem is with the sparks so I will get them change on Monday.
I also notice that my car is slower than it use to be. Do you think is the bypass valve?
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No CEL? If your car doesn't start, it's definitely something way more than the bypass valve
If your car starts normaly when cold or hot but do not start when warm it can be fuel pressure regulator.
When you say warm, you mean the car( temp of water)? The problem appears randomly, in all climate condition. It appears when the car is hot, but not always. If I start the car 12 times in 4 days, then the problem will appear 2 times.
The bypass valve question was for the power loose question.
Today I notice that if I leave the climate control on when I switch of the car, it will be on the next time I turn the switch to power (on click from starting the engine). Is it supposed to do that?
I meant cold and hot engine, also warm engine.
Regarding CC- it is that way if you switch off car while CC is ON it will be ON after you start engine again.
Check your Temp Sensor. The same thing happened to my car with me. I changed it and it's all better now. It sits on the back of the engine, a blue plug with 4 wires in it.
The think up out the temp sensors sounds right! Is there a way to tell if the original part is damage? How expensive is the replacement of this part? If I had problems with my fuel-pressure-regulator (like Nenad suggested) what other symptoms will I encounter?

Greece= 2004 European Football Champion
Dog, the coolant temperature sender costs about $15 US with gaskets and clip. It is very easy to change:

Drive the car until it is hot. Allow it to cool down for one hour. Raise the bonnet and release the coolant tank cap to release the coolant pressure. Close the cap. Allow the car to cool overnight.

In the morning (cold engine) find the coolant temperature sender on the back of the head. It is to the left and back. Release the electrical connector and set aside. Release the clip from the sending unit and remove the sending unit. Air will be sucked into the coolant system - this prevents coolant from leaking out too badly. Recover the oring gasket from the seat of the sender.

Place the new gasket on the new sender and insert it into the fitting. Insert the clip to secure the sender. Connect the electrical connector to the sender.

Have a beer and thank yourself for saving some $$ at the repair shop. :)
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Thanks guys for all your help.
I do not experience any problem with the temp gauge on the dash. It looks to me that it’s working right, showing 90 Celsius when warm and 0 when cold.
But the problem appears only when the car is 30-60 Celsius and I try to start the car. Did you have the same think happening? (The temp sensor working correctly and the problem with the car starting)
What I am trying to find out is the rezone that the sensor will not work.
Does it work ok only in the max and min of the temps?
The sensor has two circuits - one to the ECU and one to the dash. If the ECU one fails, the dash will usually still work fine. That happened to me. No hot or warm starts when that happened.
Thanks for the help . :thumbup: :thumbup:
I will change the sensor first think tomorow.
Keep us up to date on this. I always read the AEB posts. I am about to hit 100K with my variant. Might not be a bad idea for myself to stock up on one of these sensors either.

Like page 67 of my field training manual reads

"Forewarned, forearmed - to know is half the victory."
- some Spanish author I cannot pronounce
Thanks guys for all the help. :thumbup: I bought the temp sensor but when I try to install it to my car I found that the problem with the old one was really simple to fix. The electrical connectors on the sensor had rust on them, leaving only one small space to contact. That why my car sometimes worked ok and same others it would not (at least I hhope...).
I also had a problem with rust on my right turn signal which I fix.
I do not know why but I have a rust problem only on engine parts, the car itself is very clean.........
I replace the n75 valve with an n75j and I order a tt dv.
The only missing from the engine compartment is the chip :sad:
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