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View Full Version : P0117 2005 Mazda 3 2.3L



samsono
10-04-2015, 02:50 AM
Hello friends,

I'm getting an error code P0117 ECT low input circuit.

http://www.obd-codes.com/p0117

Basically my CEL came on about halfway to work this afternoon while I was stuck in heavy stop and go traffic. I also noticed almost as soon as the light came on that the coolant temperature would rapidly increase at idle, but would return back to normal temperature once I got moving again. The coolant temp would rise to nearly the top of gauge after about 30 seconds of idling (I actually turned off the engine while waiting at one intersection because I was worried it was going to overheat). When I drove home from work just now, I didn't observe the same behavior with the temp at idle, but I wasn't stuck in traffic and wasn't idling longer than 30 seconds.

I've phoned part source and was thinking of picking up a new ECT sensor in the morning and replacing it, but I'm wondering if anyone has had similar experiences with the same symptoms. I'm wondering if it's worth my while to check the wiring for damage and test the voltage first? I very quickly located the sensor earlier, and the harness itself seemed in good condition but I didn't really trace the wires themselves.

My car hasn't really exhibited the same symptoms as listed on obdcobes.com aside from the CEL, and there is specifically no mention of coolant temps rising at idle. From my searching, it seems most times the temperature rises at idle because the fan is not coming on, and I would assume that a faulty coolant sensor would cause that.

OBD codes mentions pulling temperature readings using a scan tool, but unfortunately the scanner my coworker had wasn't able to pull temperatures, and I'm hoping the good folks at part source can maybe help me narrow the problem with one of their scanners.

Ultimately I'm likely to replace the ECT sensor and hope it fixes the issue, just curious if anyone has any input before I drop the $40 on it. Especially if anyone can shed any experience on the corresponding coolant temp rising at idle symptom. The temp has increased when idling and then dropped when driving several times sporadically over the years, but that was only during hot days when I had the A/C going pretty hard (turning the A/C off would alleviate the problem).

Thanks for reading!

https://www.youtube.com/watch?v=easBmQX0IJg
http://www.mazdas247.com/forum/showthread.php?123743933-P0117-Code-ECT-low-circuit-input
http://www.themazdaforum.com/showthread.php/7399-code-P0117

samsono
10-04-2015, 12:44 PM
Just wanted to update that the cel cleared itself this morning. Literally 30 seconds after I left the store with the new sensor it went off. I idled the engine for 10min and wasn't able to reproduce the symptoms, so I'm thinking the wiring harness came loose and just needed to be removed and reattached.

Hope it's resolved because the sensor was nearly 50 bucks.