Hi I just started my car and saw that the temp gauge not going up and just stay at the bottom. I left it running to see if the fan will turn on and it sure did. I plugged a ob2 reader in and check the ect and shows around 87-91C. I measured the coolant temp sender and got a reading of .695ohm. Do this mean the sender is defective?

 

Remember that there are TWO sensors for coolant temperature: One single-wire sensor for the gauge and a second two-wire sensor for the ECU. Since you have good data at the ECU, the two-wire sensor is good. Check the single wire plug to see if there is any damage to the wire/plug... and if you don't see anything obvious, then replace the single-wire sending unit.

 

I see that the plug is alittle cracked. if I measure the wire when key on it should have 12v correct? how do people change out the wire plug? just cut and replace the plug?

 

No voltage... it is a resistant ground. If you want to test to see if the gauge is the problem (assuming that the wiring is good), you can turn the key ON (engine off), unplug the single wire sensor and touch the wiring end to ground. This will cause the temperature gauge to rise quickly toward FULL HOT... leaving the wire grounded for too long will damage the gauge cluster, so it is best to have someone sitting inside the car to tell you whether the needle moves toward hot or stays in the same place... this way you can remove the wire from ground quickly once you have determined that the gauge in fact works or not. If so, replace the sensor.

You can cut the wire a couple of inches from the plug end and replace it with a used similar wire from a junkyard car engine harness... just give yourself enough room to cut and splice each piece, and make it long enough to get the old "crispy" wiring close to the plug removed.

 

I got a aftermarket sender from Amazon to try it and the gauge works but the needle doesn’t go to the middle. Is it defective? Should I buy an oem one?

 

Slightly below the middle (more like the lowest third) looks about right if your engine is at operating temperature.

 

ya its at operating temperature. I always thought it will be at the middle. thanks

 

Believe it or not... in the middle actually is starting to get HOT. I think your needle position in the photo above looks just perfect.