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BOTLFEDLT1 · 08 May 2007, 04:58 am

Experiencing poor fuel mileage and have exhausted all of the normal fixes (i.e. proper tire inflation, new plugs/wires, clean airfilter etc) ? Something that might not be so obvious that can cause crappy mileage is a faulty coolant temp sensor. I just found this out yesterday and thought Id share.

I was changing my water pump and decided to test the sensor before putting it on the new pump with a multimeter. The sensor was showing infinite resistance (i.e. open circuit), so it was telling the pcm that the engine is always cold, so in turn, the pcm tells the injectors to spray more fuel as if its in warm up mode.

08 May 2007, 04:58 am	#1 (permalink)
BOTLFEDLT1 Senior Tremekian Join Date: Feb 2006 Posts: 1,046 BOTLFEDLT1's Gallery	Fuel economy Experiencing poor fuel mileage and have exhausted all of the normal fixes (i.e. proper tire inflation, new plugs/wires, clean airfilter etc) ? Something that might not be so obvious that can cause crappy mileage is a faulty coolant temp sensor. I just found this out yesterday and thought Id share. I was changing my water pump and decided to test the sensor before putting it on the new pump with a multimeter. The sensor was showing infinite resistance (i.e. open circuit), so it was telling the pcm that the engine is always cold, so in turn, the pcm tells the injectors to spray more fuel as if its in warm up mode. Last edited by BOTLFEDLT1; 08 May 2007 at 06:35 am.