Multiple coolant temp sensors failures
Thread Starter
Intermediate
Joined: Sep 2017
Posts: 42
Likes: 4
Multiple coolant temp sensors failures
Hey all, evert few months I’m having the coolant temp sensor fail so I replace it and all is good before failing again months later. Anyone else ever have this issue?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,642
Likes: 4,082
From: Cape Coral, Florida
Did you use an OEM sensor or aftermarket ??…there are a lot of junk aftermarket parts out there these days…any DTC’s stored ??…did you check the electrical part of the circuit before installing the new sensor ??…it’s a simple 2 wire thermistor circuit…a 5 volt reference voltage and a ground…if you remove the sensor connector you’ll see -38 degrees or so and if you jump the terminals together you’ll see it max out !!
Thread Starter
Intermediate
Joined: Sep 2017
Posts: 42
Likes: 4
Did you use an OEM sensor or aftermarket ??…there are a lot of junk aftermarket parts out there these days…any DTC’s stored ??…did you check the electrical part of the circuit before installing the new sensor ??…it’s a simple 2 wire thermistor circuit…a 5 volt reference voltage and a ground…if you remove the sensor connector you’ll see -38 degrees or so and if you jump the terminals together you’ll see it max out !!
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,642
Likes: 4,082
From: Cape Coral, Florida
If the ECM gets a low temp reading from the ECT it's thinking it's cold outside and will increase injector pulse width (like a choke on older cars) and richen the mixture,.,that's what you were experiencing...it will do this only for a short time until the engine warms up. the idle will also increase with the lower ECT temperature...On your car anything that says "sensor"..O2 sensor, crank sensor, ECT sensor etc should always be replaced with OEM...and never assume a new part is good...I recently had a bad O2 sensor on my car and went through a bad "new" Delphi sensor, 2 bad "new" Bosch sensors until I replaced it with a good new Denso sensor...if you have a DVOM you can check for 5 volts and to check for ground hook a test light to B+ and probe the ground wire...this is done with electrical system energized...the test light will illuminate if the ground is OK or if you jump the 2 wires together it should read the max temp and I can't remember the temp...a thermistor circuit is the only type of sensor you can do this on...on other circuits jumping a circuit this way can "nuke" your engine computer. Video below !!
