Mazda Protege This compact model offers an economical solution for the need for a sporty sedan or wagon.

Yet another p0118 code...

Old 11-13-2018, 03:04 PM
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Default Yet another p0118 code...

Hello guys and gals,
I have a 2000 Protege, auto with the 1.8 engine. The problem I am having is with the coolant sensor wiring, I believe.. The sensor itself tests fine, and the temp readout on the gauge seems to be correct. But when I test the terminals to the sensor connector I get 12 volts instead of 5. this is triggering the p0118 code from the ECU. I thought I had the correct pins to the ECU, but the continuity from the ECU to the connector doesn't seem to be correct. This is preventing me from definitely figuring out if I have a short in the wiring, so I don't want to cut and splice wires until I am completely certain. Also, if anyone could, would you confirm both sensor wire number/color, and if these go directly to the ECU without any other input from any other sensor? In other words, If I run 2 wires directly from the sensor to the ECU, would anything else be affected? This entire problem seems to be causing the ECU to thing that the car is always warm, under any actual temperatures, making it very hard to start. Once the car is actually warm it runs fine. I have tried a different sensor, and a different ECU with he same results. What am I missing? Yes, I already searched, but the other posts with the same code seemed to be slightly different, or didn't elaborate enough, and no one mentioned reading 12 volts at the connector.

Thanks a bunch in advance,

Last edited by SupSayZ; 11-13-2018 at 03:07 PM.
Old 11-16-2018, 10:41 AM
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Well....does anyone have a wiring diagram or the ECU pinout for both the 99 and 2000 1.8? thanks!
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