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Check Engine Light - P0125


Burke25
05-04-2009, 03:21 PM
I recently had my check engine light come on in a 2001 ZX2, and the code I am getting is P0125 - Closed Loop Fuel Ctrl Insufficient Coolant Temp. I thought maybe the temp sensor that goes in the engine block was bad and replaced it, but no such luck.

Also, the temp gauge on the dash constantly reads that the engine temp is "below the cool line", but heat is coming out of the vents.

Any insight as to the problem would be appreciated!

toddman67
05-04-2009, 07:11 PM
Someone from another post had the same symtoms, same car,same code. It ended up being a bad thermostat and low coolant level in the O-flow tank.

ricebike
05-04-2009, 09:48 PM
stuck open thermostat... if i recalled correctly from that other thread...

Burke25
05-06-2009, 08:57 AM
I will replace the thermostat this weekend and hopefully the problem will be solved. Sorry about not seeing the previous post, I'm new to this forum!

ricebike
05-06-2009, 10:46 AM
hmm, seems like it's just one of the possibilities:

http://www.automotiveforums.com/vbulletin/t352809.html

did you reset the car's pc after you changed out the sensor the 1st time?

maybe it can also be the wiring to the sensor?!?

Burke25
05-06-2009, 03:11 PM
hmm, seems like it's just one of the possibilities:

http://www.automotiveforums.com/vbulletin/t352809.html

did you reset the car's pc after you changed out the sensor the 1st time?

maybe it can also be the wiring to the sensor?!?

Last weekend, I changed out the temperature switch (the part that goes directly into the engine block) and that didn't fix the problem. I reset the PC and the light came back on two days later, showing the same code PO0125.

I am going to give replacing the thermostat a shot this weekend and hopefully that will fix the problem. I guess my next step after that is the wiring. I will keep you updated. Luckily the cost of these parts is not too high...

Burke25
05-10-2009, 05:10 PM
Hope I'm not jinxing myself, but replacing the Thermostat seemed to do the trick!! Thanks to everyone who helped out!

ricebike
05-11-2009, 05:57 AM
thanks for the reply, burke!

should help someone else in the future when they'll be searching for this similar problem

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