Leaving a Scanner Connected to a Car

I have a 2007 Nissan Murano that about once a week needs about 4 turns of the key to start. The car has about 80,000 miles, is regularly serviced and does not have the check engine light on. The problem only seems to occur when the engine is hot. I took the car to the dealer who, for $200 plus labor, offered to hook the car up to their machine but told me he didn’t think it would isolate the problem unless the car failed to start when it was hooked-up to the machine.

OK, my questions: would it be worth buying a scanner like (http://www.actron.com/product_detail.php?pid=16362) and leaving it connected to the car to record what happens when it fails to start and would I be able to store that information to show to the mechanic?

Thank you.

Take your car to a local auto parts chain and ask them to read any stored codes. They’ll do it for free. If there’s a code, write it down. If there’s no code, having a code reader permanently connected won’t help.
Either way, you don’t need to buy a code reader.

Do yourself a favor and don’t go to the dealer to fix this problem. Use the “Mechanics Files” section of this site to find a recommended independent mechanic in your area.

Next time it doesn’t start first try, do the following:

  1. Turn ignition off.
  2. Turn key to “run” position but do not try to start the engine.
  3. Wait several seconds, then try to start the engine.

If that helps, you may have a fuel pump problem. Leaving the key in “run” for a few seconds before starting lets the fuel pump build fuel pressure.

There is a torque app for smart phones and apparently the basic version is free. You will just need the OBD II connector that apparently is sold on ebay or amazon for ~$30 from what I have been told. You can then keep it connected. But as mentioned above, this would only read codes if there are any. It could also give you live performance data, but not sure if it would help with a no start situation.

I think it is beginning failure of the fuel pump. It will throw no codes. Next time no start leave the key in the on position for 10 seconds then try a start. If it fires right up replace the fuel pump.

Leaving it connected while driving is a common practice. The instructions will tell you this. Usually it is done if you want to verify that the drive cycle has completed and the monitor is in ready status.

There is one problem with this idea. Before you purchase the scan tool, which states directly that it records live data, talk to your mechanic beforehand. Get a quote for him to read the live data, and the necessary steps to collect the kind of useful information he may be able to read. There is still a diagnosis that needs to be performed, and he may want to confirm it collects the right kind of data before agreeing to use it.

Thanks for the replies. I’m going to get the fuel pump checked.

Guys, a professional mechanic at a shop would probably not want to deal with the customer’s personal actron code reader

He’d want to diagnose it from the beginning, using his own scanner and whatever other tools he needs to figure it out

I would check for two things for a hot no-start condition.

The first would be test the residual fuel pressure. If the fuel pressure drops to zero as soon as the hot engine is turned off, this will cause the fuel in the fuel rails to start to boil. This is vapor lock.

The second would be a crankshaft position sensor being effected by heat. This can easily be tested by taking a heat gun and heating up the sensor. If the engine doesn’t start while the sensor is hot, but it does start once the sensor cools down you know it’s the crank sensor.


Yep. Not every problem will set a trouble code so a scanner will not tell much for a sticking injector or failing fuel pump. Its one tool but not the end all.