I have a 2002 Infiniti i35. It's always run great, but it has been burning oil due to leaks in the valve covers and cam sensors, so I replaced the valve covers and seals and the cam sensor o-rings this weekend. The valve covers, intake manifold, and all of the electrical plugs are back in place.

The engine will crank, but will not start. I connected an OBDII scanner to my car, and it will not connect. I verified that the scanner works on our other car, a Mazda CX-5. I checked all of the fuses and fusible links with a multimeter, and they are all intact.

I did make one error during reassembly. I had forgotten to disconnect the battery, and when I was plugging the harness in the front of the engine back in, one of the plugs (a red one), which has exposed pins, touched a ground and sparked. So I'm worried that I either damaged the ECU or security system.

The reason I'm wondering if its the security system is that, when I lock the doors (with hood closed), the security light stays on for 30 seconds, then goes out. It doesn't blink like I remember it doing.

Another part of me suspect a problem with the cam sensors. However, I never removed the sensors from their plugs, so I don't suspect any electrical problems there.

I apologize for the lateness in response here. Have you found a fix for your problem?

I have run into a similar issue like this before. It's possible that your key is acting up in it, causing it not to start. Try inserting and removing your key quickly 5-7 times and then try to start it as usual. Sometimes the chips in those keys begin to fail are trigger the security system to not lot the vehicle start.