Coolant temp sensor code thrown, replaced it and still no good.

[MadTechMike]

Hey guys my ECU threw a coolant temp sensor code and i replaced it still runs like crap, 10:1 afr's at idle, i take the plug out and it doesn't change the idle. Would it make sense that i might have a harness issue? Is it feasible to just make my own wire to the ecu from the sensor? thanks.

[CSUPUEBLOTIM]

Does your temperature gauge swing all the way hot or not move at all by chance? If so you might have a short to ground or open in your circuit. Typically both will set code cause it should never read 0 volts and never read 5 volts which is what a short or open would cause.

[MadTechMike]

my temp gauge seems to be working perfectly.

[Hijacker]

Does your temperature gauge swing all the way hot or not move at all by chance? If so you might have a short to ground or open in your circuit. Typically both will set code cause it should never read 0 volts and never read 5 volts which is what a short or open would cause.

The ECU uses a different probe from the dash.

Before you run an extra wire from the ECU to the sensor (which you'll have to run two I think. One for the power and the sensor uses an ECU ground to ground), I would double check with a multimeter that your harness is at fault.

[MadTechMike]

i tried to get something small in the clip to see if i was getting voltage, but i couldn't get anything in there. Could i just strip the wires?

[CSUPUEBLOTIM]

Stripping the wires is the last thing you usually wanna do. Have you tried like a paper clip and pushing it through around the protective covering?

[MadTechMike]

i tried to get a paperclip in there last night, didn't seem to work, but i guess i'll keep trying. Thanks guys for the help!

[BLACKDIAMOND]

HEY I HAD THAT SAME ISSUE!!!! I REPLACED THE SENSOR AND ALL. WHAT IT WAS IS THAT THE WIRE GOING TO THE ECU LOOKED LIKE IT WAS CONNECTED BUT THEN I TOOK OFF THE CONNECTOR (ECU HARNESS) I NOTICED THE WIRE WASNT PUSHED ALL THE WAY THROUGH. I PUSHED IT BACK IN AND NO MORE CODES. GIVE IT A SHOT. I LEARNED THE HARD WAY NEVER TO OVERLOOK THE SIMPLEST THINGS! MANY TIMES! LOL

[MadTechMike]

well that wire wasn't loose or anything, i could only get a .1 volt reading from the coolant temp sensor(I don't know what its supposed to be). This time i started it (took a few tries)and it ran right away at 10:1 afr usually it starts and runs at 13.5:1. I gave it some gas and then backed off real fast and it goes lean..like 15-18:1 is this normal? I thought i checked for all vacuum leaks..
Modified by MadTechMike at 10:49 AM 7/31/2008

[Hijacker]

I've had corrosion in the plug also cause a bad temp sensor code as well. I just remembered that.

Tim, I think you're still getting the single wire dash sensor mixed up with the dual plug ECU sensor. There is no protective covering for the ECU plug, it should be a red plug wth the obnoxious clip.

I believe that plug is the same as some standard injector plugs. You just have to shave the keyed notch on top of the sensor to make it slide on properly. One of my friends has replaced that plug before with a low cost part from Advance

[MadTechMike]

well, i went ahead and rewired the CTS plug, it now starts when its warm, surging isn't nearly as bad, still surging and running rich but not as rich, i check the ecu for codes, it threw code 55 which is no malfunction so i think i eliminated one more problem. The vacuum is low (19lbs) so i still have a small vacuum leak. Thanks dudes for all your suggestions.