99 ZX2 p0117 error

atillamaximum · 10-22-2008, 08:15 PM

About 2 weeks ago the check engine light came on. At first there were no running issues I noticed (millage was starting to decrease but didn't notice yet). The next day I took it to an autozone and they hooked up their code reader, and the engine was reporting unusual coolant temp reading, possible causes coolant temp sensor or thermostat. Both were an easy job so I replaced both, only readily available thermostat was cheap 185F job, previous looks like it may have been original, but was definitely of superior craftsmanship. I have it all back in place checked no leaks, unhooked battery (was completely out of the car for about a day).
After assembly the the first run seems to go ok, check engine light didn't come on ( was bout a 15 min trip, 5 city 10 highway). After first run it sat for a work shift, when I started it the check engine was immediately on, also the radiator fan turns on immediately. I took it back in to check error code and got p0117 again. I have checked the wire harnesses to the temp sensor and appear fine. Temp gauge reads normally. Symptoms have gotten worse, low millage currently 20mpg, I got 35 in September, high RPM idle, first starting the car now the idle stays at 2k for about 10-20sec then settles slowly to about 1-1.3k after 1-2 minutes. Also, after running the car till it gets to normal operating temperature 180-190 then turning the car off it will not start again until the car is fully cool, (by start I mean turns over but does not ignite, there is spark from the plugs). Anyone got ideas?
Car:
1999 zx2 (hot) MTX5. Stock except generic cold air intake,

atillamaximum · 10-22-2008, 08:44 PM

Also, the car has 152k miles.

ZX2Fast · 10-24-2008, 03:30 PM

You have to use a 192-195 degree thermostat. Otherwise, the car won't reach closed loop and your MPG will suffer. That code could just indicate an open thermostat or it could be a bad wire going to the sensor, or a bad sensor.

atillamaximum · 10-25-2008, 02:33 PM

Put in a 195 thermostat, put it back in place checked sensor and wires best I could and still have same issue. Tested temp sensor in a friends zx2 and his in mine same issue on mine but no problems in his. Do you know where the wire for the temp sensor ends up and which pins they would be?

ZX2Fast · 10-26-2008, 12:17 AM

The ECT input is the same as the other regulated inputs from the other sensors. That common wire is the gray/red wire at the sensor and comes right off the TPS and the IPS sensor (probably not important since you don't have codes for those sensors) but the return wire (if there is a problem) is 99% the likely culprit. From the ECT sensor it is light green/red. When it gets to the PCM it is blue/white. You probably know how to use a continuity tester, so test the wire (with the sensor unplugged) for continuity between the ends. You should get a closed circuit. Also, test that wire between the wire and ground. You should have an open circuit.

atillamaximum · 11-11-2008, 06:31 PM

Well, I did a bit of checking and can't find an issue with the wire, Although in my searching I removed the module that is under where the stock air box would be and that unit is terribly rusted, and water has apparently been entering it for some time. I'm getting a replacement and seeing if that fixes it.