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Matt
Matt, Engineer
Category: Nissan
Satisfied Customers: 20593
Experience:  BEng hons Mech engineering, worked in auto industry for 22 years on engine, transmission and suspension design
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I have a 2003 Nissan Pathfinder that starts and runs fine

Customer Question

I have a 2003 Nissan Pathfinder that starts and runs fine when it's cold but won't start when it's warmed up. The starter turns the motor over fine but it won't start when it's warmed up. Throwing no codes.
Submitted: 8 months ago.
Category: Nissan
Customer: replied 8 months ago.
If I let it cool down for 3 or mins it starts fine and runs fine.
Customer: replied 8 months ago.
I already replaced the starter and the fuel pressure regulator. I also recently replaced one of the oxygen sensors.
Expert:  Matt replied 8 months ago.

Hello

whats most likely that a major sensor like the crank speed or the MAF meter is failing as they warm up and expand?

This could be a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;

Airflow meter

Crank position sensor

Cam position sensor

O2 sensor

Throttle position sensor

unplug each in turn and use some switch / contact cleaner spray on the pins to ensure its all grease / dirt free

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.

Check the resistance of the spark plug leads ( 13-15Kohm / metre) and replace if any doubt or high resistance - Also replace the spark plugs if any of them fail this checklist:

http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

if this is OK then I'd consider replacing the crank sensor

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