Honda Genuine 37870-RTA-005 Engine Coolant Temperature Sensor

Worked and for a great price!

I own a 2007 Honda Civic Si. The sensor seemed faulty as a CEL was thrown and I scanned and discovered a p0128 code (Engine coolant related). My first thought was the thermostat but also found via online searches that it can also be due to a faulty ECT sensor. Honda quoted me $82.99 and though it was in stock, the amazon seller listed it for $46.92 with 2 days prime shipping. It was a no brainer. Installation, I'd give it a 3/5 stars difficulty wise as it was fairly straight forward, but quite a pain to access while the engine is in the car. I had to remove my complete stock intake air box (didn't need to remove the intake arm). There is also an engine harness that is clipped onto a small aluminum/steel bracket that prevents you from accessing the sensor and clip which needs to be removed using a 10mm socket and ratchet (assuming you're able to unclip the large plastic cover that clips the harness to the bracket), and a deep 17mm socket would not clear the sensor as there's a metal hose blocking access. Thankfully I had a 17mm gear wrench that fit the sensor and allowed extraction. The oem O ring was stuck in the engine which I took out using a small flat head screw driver. The problem looked like an oil leak filled the sensor clip which may have failed. The sensor was also worn and looked a bit rusted. Once installed, everything is cherry. I'd highly recommend it.

Looks like the original.

For whatever reason this small sensor has an important part in the ECO of the Honda v6 engine. I replaced this and added a muzzle to allow the back side cylinders to keep firing and stop the problem of fouling plugs and cylinders that eventually fail. After installing and driving awhile the engine computer cleared all codes and runs fine. No problems driving from Chicago to Los Angeles.

Did the trick !! Back up and running !!