UK-POLOS.NET - THE VW Polo Forum

Hello, mine is a 9N1 2003 1.4 16V .
I had similar symptoms that half the time it would not start but eventually stammered to running normal by turning over and over for about 30 secs with a cloud of unburnt fuel.
The web led me to suspect the Coolant Sensor sited on the right of the head block as you see it.
Hard to believe right? however this sensor tells the engine the temperature and affects the fuel delivery accordingly.
The old sensor was reading an open circuit so replaced myself with a new one for only £6 (ebay) which read about 1500 ohms which is right.
Its fixed and starts and runs great. Worth a try for your problem or you can test the old one with a multimeter without a purchase.
Sensor resistances are in the Haynes Manual, start of the coolant section. FYI the sensor resistance reduces with a higher temperature.
Regards,

Good result, I have not had to replace that sensor on an older engine as my wife's 2002 9N Polo 1.4 with the BBY engine never had these issues, but, due to getting a few logged sensor duff signals on my older daughter's late 2009 Ibiza 1.4 with the later B?? engine, I discovered that the heater stopped working as well as it did before, seems like the correct way to replace the engine coolant sensor and get air out of the system is to keep filling the coolant until the coolant flowing out through that sensor hole is free of bubbles then continue filling while fitting the sensor into its opening.

Other more recent issues with starting in hot temperature seems to be a failed or faulty EVAP solenoid, that is being reported by SEAT Ibiza 1.4 with the later B?? engine in summer in hot areas of the world!

RUM4MO wrote: Tue May 10, 2016 9:30 am ciclo, there have been quite a few cases where intermittent poor starting has been due to a defective fuel pump relay, well on the Ibiza forums. I have asked the question about when this starting problem occurs as there is another problem turning up with these engines but only usually only when the weather (temperature) is hot.

Considering the possible age and mileage of that car, I was thinking that it would be too "young" to have TB or COP or plug problems.

Has there ever been a solution for this? I'm having the same issues with my 1.4 6R 2012 model and it seems to be affecting me in the warmer temperatures. I'll be waking up a little bit earlier later to check how it starts in cooler weather as it's summer here.

Whenever I try and start the car in the garage which tends to build up humidity, the engine turns over but does not start. Usually after the second try I will floor the gas pedal and it will start... Been reading so many different articles and would really like to find the issue as soon as possible. Once the engine is warm it starts very easily.