No spark after minor accident

Tiny
MAGAURODNEY
  • MEMBER
  • 2012 VOLKSWAGEN POLO
  • 1.4L
  • 2WD
  • MANUAL
  • 242,200 MILES
Hi there,

Please assist me with solving the problem with my car. No spark after minor accident where we replaced bumper. I tried with four auto electricians and they didn't get the cause. They have tested all fuses and computer box.
Thursday, April 11th, 2019 AT 11:54 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi Magaurodney,

Just going off what you stated, I would put my money on the fact that there is an issue with the crank sensor (or you engine also has an RPM sensor that is used as well). This sensor is required for identifying current engine position while cranking. So I will make a guess and say that your engine is cranking when you turn the key but it just does not fire, which is why you described this as no spark.

The reason you don't get spark if your crank sensor was damage during the accident is because the PCM (computer) uses this sensor to find where the crank shaft is while you are starting your engine. If it does not know where the crankshaft position is then it will not know when to fire the spark plugs and so it will not fire the plugs at all. Hence your issue of no spark.

I attached a couple of guides that will help explain the importance of the crank sensor.

Unfortunately, I don't have a diagram for your specific vehicle. However, your auto tech should and I also included a previous post of a similar issue. There is actually a video on that post about 3/4 of the way down the page that shows an auto tech on a similar engine doing this type of testing. Pay particular attention to the final minute (3:40 minute mark) of the video. This is where he discusses the crank sensor and RPM sensor.

https://www.2carpros.com/articles/how-a-crank-shaft-angle-sensor-works

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

https://www.2carpros.com/questions/2003-volkswagen-polo-vw-1-4-petrol-will-start-over-past-3-weeks-sons-been

Please let me know if you need more info and I will be happy to help.

Thanks
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Saturday, April 13th, 2019 AT 7:14 AM

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