Help Please!

This started last wednesday, raining on the way to work, 'service engine soon' light came on. After work, it took about 30 attempts, and 10 minutes to get the engine fired up. OBDII scan noted P0117, Engine Coolant Temperature Circuit Low Input. I replaced the sensor this weekend, but no change.

Once I got it fired up today, I was checking for loose hoses behind the intake manifold and the manifold to firewall ground wire was very hot. Maybe just from so many cranks.

Got it scanned again today, same thing...P0117.

Don't know what to do. Don't want to take it to satan.

Any help is appreciated!

 

You need to go through the cooling system circuit with a multimeter and check various points.. A hot ground may be from too much resistance somewhere in the coolant systems' circuit.

Here's some schematics to help you out

 

You need to measure voltage with an on-board computer. Odds are, it is measuring under .9volts (so the vehicle thinks it has a coolant temp of 284*F.

 

Did you ever have the codes cleared? It will store that trouble code even if you fixed the sensor. It is a 1 trip code which means if the conditions are present and it fails it will immediately turn on the check engine light. If you already replaced the sensor with a known good and that code still appears right away after clearing you have a wiring issue. Ironically you said it happened while it was raining also which would lead me to believe it is an external wiring issue.

 

Thanks for schematics BEkevo. I will try this, once I figure out how to do it. Not much experience with the multimeter, but I do have one.

 

I may need some additional guidance on this. Can a multimeter be used, and where should I check the voltage? The connector to the coolant temperature switch?

 

I simply disconnected the battery when I changed out the coolant temp sensor to clear the code...hope this is correct. Once I tried to restart the car, the service engine light was not lit, but after a few attempts to crank the car it came back on.

Also, I noticed the cooling fan was on right away once I got the car started, when the engine was still cold/not yet warm.

 

Without a proper scan tool it is a little difficult to diagnose the issue. You visually inspect the wire and connector going to the temp sensor. Check for open insulation or if it has rubbed through somewhere

 

The cooling fan coming on probably means the ECU thinks the engine is hot. A short or water in the wiring could do this.

Grounds should never get hot. No wires should get hot. If the car has had an engine swap maybe all the grounds didn't get reconnected. This also can screw up readings from under the hood.

Get the ECU scanned to see what the the ECU thinks the coolant temperature is. Explore and clean the engine grounds. It sounds like you may need the services of a good shop.

 

The car is mostly stock, except for the usual intake and exhaust mods. Only about 55k miles. The clutch was replaced about a year ago.

I'll try and get a OBDII scan tool somewhere, and try and use the schematics provided above to start checking the wires.

And perhaps rent a nice economy car until this gets fixed. Takes alot of cranks to get it running when cold.

This sucks.

 

The OBDII tool I have won't give you the coolant temperature. You need Evoscan and a laptop or some tool a shop may have.