2001 Nissan Sentra - wont start in the cold


#1

I bought a used 2001 Sentra for my son in July 2007. The car ran fine all summer and fall. This past January, we had an extremely cold day where the car would not start. I replaced the battery and it still would not start. After 5 days in the shop all they could say was that it had been flooded and that it was running fine now. They did some diagnostics but found nothing. About a month later we had another extrem cold spell (single digits) and again the car would not start. I took it to another mechanic and again, he could find no problem other than flooding. He spoke to the Nissan dealer thinking it may be some barometric sensor but they didn’t think this was the case. Last weekend the car did it again! This time we did not have extreme cold but did have a clear change in the weather and barometric pressure. I was told by the second mechanic how to get the car started when this happens…take out the fule injector fuse, crank several times, replace fuse and start. It worked! However, this doesn’t really fix the problem. Does anyone have any idea what the problem could be? I’ve already spent nearly $500 to be told there isn’t anything wrong that can be diagnosed. Robert (Western Maryland)


#2

Did anyone test the coolant temperature sensor for proper operation?


#3

This engine coolant temperature sensor (cts) is the primary sensor the engine computer depends on to set fuel flow during start, and run. If the cts is sending the wrong signal (it may be erratic), the computer can cause the engine to flood. The engine computer won’t know that the cts is wrong; thus, it won’t set the check engine light.


#4

Each time this happens the check engine light has come on but the mechanics have said that they are not picking up on a failed systems and they have just cleared the computer. Is the cts and easy, inexpensive fix?


#5

maybe a stupid question — but could the coolant temperature sensor be erratic because the coolant needs replacing?


#6

It would only be erratic if the coolant level is too low.

The CTS is a cheap and easy repair, but don’t go throwing parts at the car just yet. If the Check Engine light is coming on, there most definitely will be one or more diagnostic trouble code stored. Your mechanics aren’t being honest with you or there is a communication problem. With the Check Engine light on, take the car to Advance Auto Parts, AutoZone, or a similar store for a free scan. Report back with the exact code(s). They will be in the format of P0xxx.


#7

Next time or even right now (the codes may still be there with the light off) you need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.


#8

If the engine floods as it is cranking, it’s likely the cts. The cts resistance, and voltage, can be measured; but, it needs to be measured at the temperature that the flooding is occurring (freezing). When the engine (and, thus the cts) are warmed in a garage, this condition of measurement can’t be fulfilled.
If the engine is already flooded, before it is cranked, that could be from the fuel injectors bleeding down (into the engine intake) while the engine is shut off. This can, also, be checked. A fuel pressure gauge is installed. The fuel system is pressurized by turning the ignition key ON a few seconds. The key is turned OFF, and the fuel pressure is monitored. The fuel pressure should hold for 30 minuets. If it doesn’t, the fuel injector(s) are leaking, or the pressure regulator is releasig fuel pressure, or the fuel pump check valve isn’t holding the pressure.


#9

There is a no-cost-to-you safety recall Campaign Number, Case 03V455000, R3021/R3022 for your car. It’s to change the Crank Position Sensor (free). The problem is for stalling, performance problems, starting problems. Get your car VIN number, and call 1-800-nissan1. There is, also, a recall, on some VINs, for the foam in the ECM (engine computer) box causing some problems.