Repair guides and support for the 5th generation Honda Accord coupe, sedan, and wagon.

48 Questions View all

temperature gauge pinned hot

when starting the car the temp. gauge jumps to red hot ....I've been driving the car for 15 minutes max. one way thinking that the car may overheat but so far the car seems normal at these short distances.

Answered! View the answer I have this problem too

Is this a good question?

Score 1


Hi, Have you checked the coolant level in the coolant reservoir?


Yes, coolant level is fine! The temp. gauge goes to red hot or pinned as soon as I start the car cold. And...after approx. 15 min. driving locally, the engine doesn't seem to be overheated. so I'm assuming that the thermostat is working fine. I'm just afraid to drive it longer or farther when the temp. gauge says red hot.


Add a comment

1 Answer

Chosen Solution

Hi @jamesjew,

Since you are experiencing no overheating problems the most likely cause is that the engine coolant temperature sending unit is faulty. This sends a signal directly to the dashboard gauge. There is another coolant temperature sensor close by which sends a signal to the ECU to help in engine management. You shouldn't get confused between the two as the one you want only has one wire and the other has two.

Here is an image showing the two sensors. The one on the left, where the single wire black connector has been disconnected is the sensor sending unit to the dashboard gauge, the one on the right with the grey connector (and being held by fingers) is the ECU sensor.

Block Image

Not quite certain if my figures are correct , but to test the sending unit, disconnect the single wire black connector and using a DMM (Digital Multimeter - Ohmmeter function) measure the resistance between the sending unit terminal and earth (or ground - the engine block will be earthed). With a cold engine the resistance should be approx 140 Ohms. With a hot engine it should measure 30-50 Ohms. If you measure around this value (or definitely not near 140 Ohms) with a cold engine then the unit is faulty and needs to be replaced.

A quick test is to disconnect the lead from the sending unit, turn on the ignition and observe the temp. gauge. If it registers 'zero' then most probably the sending unit is faulty. If however it still registers a 'full scale' reading then either you have removed the wrong lead, there is a fault in the wiring or there is a fault in the instrument cluster/temp gauge

Note: Be safety aware - always switch OFF the engine when you are going to work on it

Was this answer helpful?

Score 3


Thank you Jayeff! Your diagnosis including the photo was correct. I installed a new temperature sending unit this morning and the temperature gauge is now working properly. Thanks again for your help! James


Add a comment

Add your answer

James will be eternally grateful.
View Statistics:

Past 24 Hours: 38

Past 7 Days: 240

Past 30 Days: 1,318

All Time: 7,653