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Discussion Starter #1
So I have a 2002 V6 ATQ engine. Like the title says, I stepped in the store the car spent less than 15 minutes and the the engine turns normally but there's no ignition. after waiting for 15-20 minutes it turned on normally. Normally I would just blame it on the VW gods but it happened again later that day.
 

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No start while the engine is warm is typically caused by a bad coolant temp. sensor.
 

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Discussion Starter #5
Yeah the CEL is for a SAIP insufficient flow. How do I check the coolant temp sensor/replace it if it's bad?
 

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How do I check the coolant temp sensor/replace it if it's bad?
If you have vag-com (or a scan tool capable of displaying the coolant temp data) watch the readings from cold-start to full temperature and see if they look plausible. At cold start it should indicate somewhere around the ambient temperature. At full operating temp it should be somewhere around 90ºC.

The CTS is two senders in one part. The dash coolant temperature gauge gets its signal from one side and the engine computer from the other side. One side can fail while the other still works. What typically happens is the CTS fails and tells the engine computer that the engine is cold when it's actually hot. The engine computer believes the sensor and delivers cold start fuel mixtures (rich). The engine floods due to too much fuel and won't start.

Next time this happens, unplug the CTS and see if it then starts. If the ECM is getting no signal at all from the CTS, it looks at the intake air temp sensor and uses that to guess by. Also try holding the gas pedal all the way down and cranking the engine to clear the flooded engine.

Do some searches for the procedure to change the CTS. It's not an expensive part.
 

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The coolant temp sensor is pretty cheap isn't it? Just go ahead and replace it, it's not too difficult. Just don't lose the old o-ring in the coolant flange. :icon_eek:
 

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The coolant temp sensor is pretty cheap isn't it? Just go ahead and replace it, it's not too difficult. Just don't lose the old o-ring in the coolant flange. :icon_eek:
don't lose the C-clip, either!
 

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Discussion Starter #16
So Sorry for abandoning my post my peeps... I brought my car over to my mechanic (an indy shop from russia who rebuilt a friends '01 S4) and he proceded to do the things that I knew needed to be done but not the remedy to my problem. After my valve cover gasket replace, tune up and SAIP job the car ran fine for 2 days until tonight where it left me stranded in the hood, with my girl at 2am... Worst of all no cold beverage in sight. The car shut off on me wouldn't start until it cooled down and then once we got going stalled again at the light. WTF! I'm gathering from a little research and the valuable responses here that I should get the Coolant temp sensor and Crankshaft Sensor replaced? This is turning out to be the straw that breaks the camels back, let me know if I need to do something else. I'll keep you guys posted on the progress.
 

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NB: There's a guy in another thread going through hell with a V6. Intermittent crank, but no start. We had him replace the CTS to no avail. It's now looking like the ignition switch is bad; it activates the starter, but doesn't turn on the ignition.
 

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I'm thinking engine speed sensor (crank sensor) at this point.
 

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NB: There's a guy in another thread going through hell with a V6. Intermittent crank, but no start. We had him replace the CTS to no avail. It's now looking like the ignition switch is bad; it activates the starter, but doesn't turn on the ignition.
I had that happen with my A4 a year or so back. Getting off the freeway at night, the gauges suddenly all shut off, including idiot lights, but instrument illumination was still on. It restarted fine, but the ignition switch was replaced as soon as I could get one.
 
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